Yes, but even so there are few examples when reading succseeded. Hrozny with hittite writing and language and Michael Ventrix for Linear B writing and micenaean language. Out of hundreds of work hours they had every of them an unimaginable luck and inspiration for the very 1-st step:                                                                                               – Hrozny to see a familiar sumerian sign for bread and thinking that the word would be later folowed by the word drink….                                                                                                       – Ventrix supposed to have written Pa-I-To and at some ten Km there was the ruins of the ancient harbour/town Phaistos…

Even when the writing is known cause the unknown language, even now Cretan hieroglyphic,Linear A and eteoCretan writings are not yet deciphered because the languages (minoan and eteocretan) are unknown. Maya glyphs and yukatec language, partly ” The phonetic value is known for 80% of these signs while the meaning of only 60% of them has been deciphered so far (but counting).”

Note that for sumerian writing and language at the time and nowdays there are hundred of thousend available tablets.Hrozny also had thousend of tablets in Instanbul lybrary, Ventrix had hundreds and today there are thousends of minoan tablets. One schollar,  Richard Vallance are inviting those who feel able to try to read some of them.                The existence of a minimal number of tablets is of paramount importance, as when one would test the right reading, could be checked/tested on others.

See http://mentalfloss.com/article/12884/8-ancient-writing-systems-havent-been-deciphered-yet

WHY THE DECYPHERING ATTEMPT OF TARTARIA TABLETS WOULD BE  UNIMAGINABLE HARD :

1. the tablets are singletons (they are unique of this kind).No one others of the same type are available, in order to check some reading attempts toward a correct interpreting.
2. unknown writing;                                                                                                         2.a.could have proto-cuneiform signs or                                                                           2.b. have logograms/syllabograms. Even when writing is known could not read (eg. Ezerovo ring:greek alphabet, unknown language). An distant ethnic group could write with another’s letters (tungusik inscription with greek letters, found in S.Mare Romania)
3. unknown language; if the supposed age is real, scientists are expecting a supposed”proto-euphratean language“, that means pertaining to a time before sumerian, language about scientists only imagine how could be. 
4. not sure the age; No single human in entire World, not lay down a single inscribed clay piece, even as “before writing” stage, “proto-writing” before 3,500 B.C. !
5. not known where was the scribe from !?
6. the number of resulting words/meanings is great. A number resulting from multiple “x combinations taken by Z”                                                                                 Eg. Out of only 2  greek signs “HD”, could have:                                                       har,haros,hera, heros hora, eros, era, hed, hede, ed,ede, hades, etc.                                 From R – Wikipedia https://en.wikipedia.org/wiki/R
   most Old Italic alphabets show variants of their rho between a “P” and a “D” shape, ====================================================================

   From                                                                                                                                      What is currently known about the Tărtăria tablets and the Vinča symbols? https://www.quora.com/What-is-currently-known-about-the-T%C4%83rt%C4%83ria-tablets-and-the-Vin%C4%8Da-symbols

   “The Tartaria tablets and the Vinca symbols were found in Romania and Serbia, and dated to the 5th millennium BC. The Gradeshnitsa tablets also date from the 5th millennium BC, but were found in northwest Bulgaria. The Dispilio tablet dates from 5260 BC and was found in Macedonia.
   Oscar Tay, speaks a language Answered Oct 27, 2017 · Upvoted by Thomas Wier, Assistant Professor of Linguistics at the Free University of Tbilisi. and Nick Pharris, Ph.D. Linguistics, University of Michigan (2006)
   “As I’ve mentioned in earlier answers, writing was invented independently four times, three if you consider Egyptian hieroglyphs as being from Cuneiform. All modern writing systems, and every writing system to have ever existed, comes from one of those four.

   Well, almost every. Maybe.

   First, to get a strange idea out of the way, this is not the ancestor of any modern writing systems, especially not any alphabetic ones. (See also here.)

   Second, we’re not completely sure it’s a script, or even proto-writing. It’s complex enough that it may have represented things in more detailed ways than just drawing would, but it’s probably not a “true script”, i.e., one that can represent a full language. Mathematical notation, for example, is not a true script, because it can’t represent anything beyond, well, math.

   If the Vinča symbols do represent a language, we’ve got some issues. The first problem is that they might be a clever hoax, which is always an issue in script-deciphering.

   But let’s say they are authentic and do represent a language. Just this knowledge – not even which language it was, but whether it was a script – would be incredible: we would have physical evidence of a script from Neolithic, pre-Indo-European civilization, which is also named Vinča                                                           Let’s say it is a true script – and to be clear again, it likely isn’t; this is just for an example. We’re met immediately with a rather glaring issue: most of the inscriptions, which are scattered across eastern Europe and span centuries, are very short. The issue of having primarily or solely short inscriptions also plagues the decipherment of the Indus script, but the quest for Vinča has it worse, with many of the inscriptions only one or two characters long.

   

   Approximate location of the Vinča culture. From Wikipedia.

   But let’s pretend we do have a long text in Vinča, something that unfortunately eludes its crypto-archaeo-linguistic pursuers. There are three levels of difficulty in deciphering languages:

   1. The language is known, the script is not: You have a vocabulary you can work from, provided the script is long enough and has enough context. Find some proper nouns and you’re set.
   2. The script is known, the language is not: You can read the language and likely pronounce it and maybe recognize some loanwords if there are any.
   3. Neither the script nor the language are known: Well now you have a problem to the scale of hieroglyphs, Linear B, the Indus script, and the Voynich manuscript. Proper nouns and bilingual inscriptions will be your holy grails, if you can find any.

      Vinča sits at about a 4. Not only is the language not known and the script wholly undeciphered (if it is a script at all), but their proper nouns would be nothing like those in any languages we know of.

      Worse than that, Vinča’s contemporary languages are all reconstructed, because, well, we have no way of knowing exactly what they’d be like. To reconstruct a language, you need surviving descendants; the only surviving pre-Indo-European languages in Europe are the Uralic languages and Basque, and chances are the Vinča language is related to neither.

      • We don’t know what the script says; we don’t know if it’s a script.
      • We don’t know what the language is; we effectively can’t know.
      • If we could read it, we would push history back by thousands of years.

      I leave it as a virtually impossible task to the reader, if they’d be up to it: it’s only virtually impossible, after all. Until then, to answer your question, we know little about the language it encodes, if that.”

      ==================================================================From

      START OF THE COPPER AGE, START OF INDO-EUROPEANS

      https://people.well.com/user/mareev/portal/prehistory/ancient_prehistory_timeline4.html

      
      5850 – Arrival of Neolithic farmers speaking an unknown language, bringing elements of Samara culture (6,000 BCE).
      The Samara culture was an eneolithic (copper age) culture of the early 5th millennium BC at the Samara bend region of the middle Volga, discovered during archaeological excavations near the village of Syezzheye (Съезжее) in Russia.
      The Eneolithic culture of the region is a proper name, referring to the Samara culture, the subsequent Khvalynsk culture and the still later early Yamna culture. [Yamna = Kurgan]
      Samara culture sites: Other sites are Varfolomievka (on the Volga, actually part of the North Caspian culture) and Mykol’ske (on the Dnieper). Varfolomievka is as early as 5500 BC. These three cultures have roughly the same range. Marija Gimbutas was the first to regard it as the Urheimat (homeland) of the Proto-Indo-European language and to hypothesize that the Eneolithic culture of the region was in fact Indoeuropean. If this model is true, then the Samara culture becomes overwhelmingly important for Indo-European studies.
      “Arrival of Neolithic farmers speaking a Proto-Euphratean language 5,850 BCE, bringing elements of Samara culture (6,000 BCE). The following Hadji Muhammed culture pioneers irrigation. Rivers, most Sumerian cities and crafts were named in Proto -Euphratean” [Sumer and Elam ppt]”                          ——————— see also ——————————————————-                                        Will the Indus Valley Script ever be deciphered in the absence of a “Rosetta Stone”?                                                                                https://www.quora.com/Will-the-Indus-Valley-Script-ever-be-deciphered-in-the-absence-of-a-Rosetta-Stone-1

      Hammad Shakil, interested in ancient history

      Answered Aug 29, 2018 ·

      “the western scholars who are agenda based aryanist/invasionaist make it impossible to reach a common ground for decipherment to be acceptable, even if it is deciphered lets say by indian scholars, the hue and cry raised by these agenda based aryanists will make it highly controversial (if you read posshl’s book and his chapter on indus script, you will understand why these die hard aryanists are resisting decipherment of indus script, its purely political agenda nothing else)

      i do think that the script is very much decipherable and efforts have already been made in the right direction, there are somethings to keep in mind while deciphering indus script.

      1. to embrace the fact that indus script is logo syllabic
      2. to embrace the fact that brahmi script is derivative of indus script
      3. to embrace the fact that the script decipherment has the possibility of indo european language/ prakrit
      4. to embrace the fact that the script should not used to serve western aryanist agenda and leave it an open ground for neutral scholars to decide whether the script in logo syllabic or logographic, whether it is indo european or dravidian by making credible decipherment.
      5. embracing the script is not agglutinative but consists of prefixes and suffixes.

      these facts are not accepted by western aryanist scolars because embracing any of these facts may lead to indo european decipherment, embracing brahmi script as derivative of indus script makes indus very close to achieving father of all alphabetic system status, embracing indus’s syllabic status will lead to embracing brahmi similarities with the indus script (which will lead to acceptance of indus’s brahmi like characters like compund syllables, the vowel representation of indus like brahmi script etc which will designate the script as indo european even before deciperment), accepeting the script may not be agglutinative script and may contain prefixes (which will make indo european language a possibility) being open to indo european language is like a aryanist die hard fanatic to question his faith, the western scholars are still stuck in 19th century when british colonists and german indologists had lots of fun making aryan concocted stories before indus valley civilization was discovered in the 20th century, they need to grow out of this narrow minded thinking.                                                                                                                          the present scenario paints a very gloomy picture of a script which is being on the hands of political agenda of few aryaist western scholars and indian scholars either fully towing the british colonist agendas like romila thapar or not showing any visible interest to investigate their own history through archaeology, very little indian efforts have been made to decode indus script which leaves it an open ground for western aryanist (and few tamil dravidists) to exploit.                                                                                                                        Indian government should invest more in archaeology to explore and excavate the areas which have already revealed for example, a brahmi script copper plate which dates probably from late 2nd millennium BC early 1st mil BC, not many people about this artifact but this artifact is very important to establish earlier antiquity of the brahmi script, to negate western aryanists who keep repeating the mantra of 300 BC for brahmi, we already know that indus script was functional as late as 1100 BC, this will enable many scholars to open their minds for the possibility of brahmi origin from indus and thus acceptance of brahmi phonetics in indus script.”                                                        ————————————————————————————–                                            The State of Decipherment of Proto-Elamite
      Robert Englund, UCLA                                                                            https://www.mpiwg-berlin.mpg.de/Preprints/P183.PDF

      Introduction
      With the continuing publication of the proto-cuneiform texts by the collaborators of the project Cuneiform Digital Library Initiative (CDLI)2, we are achieving a more substantial basis for the continuing discussion of the early development of writing in Mesopotamia. Cuneiform represents a system of writing with a history of over three thousand years of use, and can boast of a text corpus unparalleled in number and breadth before the invention of the printing press. Cuneiform offers, moreover, a unique view of the earliest stages of development of an advanced writing system. In a career spanning over thirty years, Denise Schmandt-Besserat has published and discussed the
      significance of a means of accountancy employed in the ancient Near East that represents a clear precursor of the first proto-cuneiform tablets. Small clay objects unearthed in prehistoric strata were termed “tokens” by Schmandt-Besserat, who wished to underscore their use as markers in an ancient system of bookkeeping. These clay objects consist on the one hand of simple geometrical forms, for instance cones, spheres, etc., on the other of complex shapes or of simpler, but incised forms. Simple, geometrically formed tokens were found encased within clay balls (usually called “bullae”) dating to the period immediately preceding that characterized by the development of earliest proto-cuneiform texts; these tokens most certainly assumed numerical functions in emerging urban centers of the late
      4th millennium B.C. Indeed, impressed signs of an array of numerical systems found in protocuneiform accounts represented, in both form and function, many of the archaic tokens, so that the forerunner role of the simple tokens in the development of writing in Mesopotamia belongs, as the editor of this volume would understand the term, to the “core knowledge” of modern cuneiformists.
      The spate of new proto-cuneiform tablets on the London markets deriving from post-Kuwait War Iraq, including over 400 new texts of both Uruk III and Uruk IV3 period date, reputedly from the ancient city of Umma, have increased the size of the proto-cuneiform corpus to over 6000 tablets and
      fragments containing more than 38,000 lines of text. Two elements provide us with a relatively firm understanding of the contents of many of the earliest cuneiform documents. First, there is an evident continuous paleographic and semiotic progression of the cuneiform sign repertory into periods,
      beginning with the Early Dynastic IIIa period ca. 2600-2500 B.C., whose administrative and literary documents are increasingly comprehensible. Second and more importantly, a many centuries long scholastic tradition of compiling and copying lexical lists, ancient ‘vocabularies’, help bridge the gap
      between proto-historical and historical context. It should also not be forgotten that the seventy years in which a limited but quite involved circle of Sumerologists has worked on proto-cuneiform have resulted
      in a number of tools helpful in continuing research, including the first Uruk sign list of Falkenstein(1936) and its revision by Green and Nissen (1987), but also in a growing number of primary and secondary publications by, among others, Friberg (1978-1979; 1982; 1997-1998), Green (1980; 1981;
      1987), Charvat (1993; 1998), and the members of the CDLI. Despite such research tools enjoyed by those involved in the decipherment of proto-cuneiform, no definitive evidence has been produced that would identify the language of proto-cuneiform scribes. The onus to make the case one way or the other would appear to rest with specialists in the field of Sumerology, since, given its later linguistic presence and the strong cultural continuity in southern Babylonia, Sumerian must be the favorite candidate for an eventual decipherment. Yet neither the evidence for possible multivalent use of signs in
      the archaic period, nor, for instance, the more sophisticated argument of a unique connection between Sumerian number words and the sexagesimal numerical system, a notational system which appears to be attested already in the token assemblages of the prehistoric clay bullae, have sufficient weight to convince skeptics. On the contrary, it seems that a strong argument from silence can be made that Sumerian is not present in the earliest literate communities, particularly given the large numbers of sign sequences which with high likelihood represent personal names and thus should be amenable to grammatical and lexical analyses comparable to those made of later Sumerian onomastics.                                                                                                                        Despite these uncertainties in the proto-cuneiform record, many factors make the interpretation of the earliest phase of writing in Mesopotamia a study of considerable reward. In Mesopotamia we are
      favored with a substantially unbroken tradition of writing in both form and function through a period of three millennia, including most importantly an exceedingly conservative tradition of so-called Listenliteratur, that is, of compilation and transmission of thematically organized word lists beginning with those of the earliest, the Uruk IV-period phase of writing; we count large numbers of inscribed tablets and fragments from archaic Babylonia, now ca. 6000, which for purposes of graphotactical analysis and context-related semantic categorization of signs and sign combinations represents a text mass of high promise; and assuming populations in Babylonia were relatively stable through time, we can utilize language decipherments from texts of later periods in working hypotheses dealing with the linguistic affiliation of archaic scribes.
      Against this backdrop, the task of deciphering early texts from Persia seems all the more daunting.
      Although these texts have played an historically minor role relative to early cuneiform, the French excavations of Susa (Figure 2) made that script the first archaic Near Eastern writing system known to us. A quarter of a century before British-American excavators of Jemdet Nasr, and German excavators of Uruk unearthed their proto-cuneiform tablet collections, de Morgan’s archaeological earth-moving machine sent to the Louvre examples of an evidently very early writing system which, based on a
      presumed genetic relationship to the later attested Elamite-speaking peoples of the Susiana plain, has been only conventionally named proto-Elamite. The proto-Elamite corpus numbers just over 1600
      pieces, with ca. 10,000 lines of text, that is, about a quarter as many as from Babylonia (still, it represents a large amount of material compared to the relatively humble inscriptions of Linear A or of early Harappan).            The publication of tablets appears to have proceeded with little understanding of the text corpus and the accounting system it represented, and with little attention paid to an accurate representation in hand copies of the texts themselves.Accompanying sign lists were published with scant thought given to the high number of signs and the likelihood that the upwards of 5500 signs in the final list attached to a primary publication by Mecquenem (1949) contained large numbers of sign variants. The list published by Meriggi (1974)
      attempted to solve this problem by including under discrete headings presumed variant graphs and so arrived at a total of less than 400 sign entries. That list was unfortunately itself laced with incorrect identifications and graphic forms of many signs, in part reflecting the wayward decision of the author to opt to follow the original, rather than the established conventional orientation of the proto-Elamite tablets. This, added to the fact that seemingly all of the signs were published as mirror images, and that the important numerical sign systems were defectively organized, makes the Meriggi list a research tool of limited value. However, proto-Elamite inscriptions have been, and will remain highly problematic in a discussion of writing because they represent but a relatively short period of literacy, beginning around 3100 and ending around 2900 B.C., after which, unlike Mesopotamia, no writing tradition existed that might have served to reflect light back to this earliest phase. The few so-called Linear
      Elamite inscriptions from the late Old Akkadian period, that is, from a period some eight centuries after the proto-Elamite age, exhibit little graphic and no obvious semantic connection to the earlier writing system.
      Still, the proto-Elamite writing system exhibits high potential and, but for its uniqueness as a largely undeciphered script of an entirely unknown dead language, has some features which might have made
      it an even better candidate for decipherment than proto-cuneiform. Among these are a substantially more developed syntax evident in a linear “line of sight” in the writing practice (see below), and in an apparently more static graphotactical sign sequence.

      From The state of decipherment of proto-Elamite – Cuneiform Digital …    cdli.ucla.edu/staff/englund/publications/englund2004c.pdf

      Conclusion
      The prospects of discovering script characteristics that could lead to a decipherment of proto-Elamite are not great, but there are some areas of promise. In the first place, the proto-Elamite texts do contain sign sequences which are distinctly longer than the average of those from Mesopotamia. The texts are therefore more likely to consist of syntactical information than the very cursory notations in protocuneiform documents. But there is a more important, second point. Statistical analysis of text transliterations should point toward meaningful sign combinations of a fixed sign sequence which could reflect speech (Figure 20). Further, the “proto-Elamites” are not entirely foreign to us. We can assume that they were a people who used a decimal system to count discrete objects, and some of their number words, in particular the words for “hundred” and “thousand,” may have been used syllabically. In proto-Elamite accounts, the numerical notations follow counted objects and their qualifications. This deviation stands in contrast to Mesopotamian tradition (we have of late seen only one other example of such a convention, namely in the 24th century accounts from Syrian Tell Beydar47), and more importantly in contrast to the first ideographic tradition in Persia itself, that is, in the numeroideographic tablets from Susa and Godin Tepe presumably imposed on the local population by Babylonian accountants. We might therefore speculate that our so-called “proto-Elamite” derived from
      a language whose numerical qualifications were post-positional.
      A first step in the reevaluation of the proto-Elamite text corpus is necessarily the electronic transliteration of all texts. CDLI staff have completed this task, and are now beginning a new graphotactical examination of the texts. The following list demonstrates the use to which these data might be put. The proto-Elamite sign M371 (two round impressions connected by a single stroke)
      appears in the accounts in initial, intermediate, and final position, in altogether over 300 attestations.As seems evident from attestations of the sign in initial and final position, it represents a discrete object counted in the sexagesimal or decimal system. A quick check of the sources confirms that the system is in fact sexagesimal. Scheil (1905:no. 391), for instance, contains clear sexagesimal notations (1N34,2N34) of objects including M371. Scheil (1923:no. 94) and other accounts imply that M371 is related to the proto-Elamite sign for male laborers (M388), possibly, since M371 is not reckoned in the decimal system, in a supervisory capacity Current work on the proto-Elamite corpus thus can draw on both internal data from the Persian documents, and on comparative data from Babylonia. The Babylonian comparisons pose again the
      question of the ultimate relationship between the two writing systems. Clearly, proto-Elamite must be reckoned to those cases of secondary script origin known from many non-literate regions in contact with literate cultures. Yet it is too facile to declare that Susa imported this idea of writing, along with
      some few direct loans, at a time when Babylonia had passed into a second writing phase at least several generations after the origin of proto-cuneiform in Uruk IVa. It is evident from our data that those elements which are direct, or nearly direct loans from Babylonian tradition, for instance the numerical
      sign systems used in grain measures, point to a period within, and not at the conclusion of the initial writing phase Uruk IVa. Moreover, the examples of numero-ideographic accounts demonstrate that both centers employed the same signs at the earliest phase of writing development. At this moment,
      direct loans from Babylonia were frozen in the proto-Elamite system, whereas they were still subject to paleographic variation in Babylonia. In the case of the number sign N39, Uruk scribes of the Uruk IV period had not agreed upon one or the other of two possible forms, N39a ( ) and N39b ( ). By the
      beginning of the following period Uruk III, standardization had dictated in the school the use of only N39a. Persian accountants chose the equally plausible variant N39b from the Uruk IV pool of signs.
      This and other comparable agreements in the proto-Elamite syllabary point to a rapid development of a full writing system once its advantages in the administration were understood. One of the more important tasks ahead of us will be an attempt to eliminate from the current proto-Elamite sign list as
      many of the very numerous variant forms as possible. We count over 1900 discrete signs in 26,320 sign occurrences in our transliteration data set, clustered around approximately 500 basic forms. Of the 1900 forms, however, more than 1000 occur just once, another 300 only twice in the texts. These
      numbers are a clear indication that the writing system as it has been transmitted to us was in a stage of  flux, in which a scribal tradition had been unable to care for standardization of characters. Nonetheless, these numbers also tell us that the proto-Elamite system, like that of Babylonia, probably consisted of a mix of ideograms and syllabograms and comprised altogether between 600 and 900 discrete signs.
      Chronologically, the proto-Elamite system fits well into the development and expansion of Babylonian proto-cuneiform. We may picture the Uruk expansion into Persia and Syria during the 4th millennium characterized in the history of writing by the appearance of a systematic means of
      accounting through manipulation of small clay counters whose form indicated both numerical and ideographic qualities. This administrative tool crossed the barrier into transaction representation on one two-dimensional surface, namely on numero-ideographic tablets, when Uruk tradition was still strong
      in Persia, but the succeeding withdrawal of Babylonian influence, occasioned by developments in the south of Mesopotamia we cannot see, left Persian scribes to their own devices. An apparently continuous administrative apparatus, and a highly adaptable bureaucracy, formed the basis for the
      development of the proto-Elamite writing system that on its surface seems very foreign, but that on closer inspection reflects much of its Babylonian heritage.
      In the meantime, debates continue about the populations which might have been in contact with or even existing within the region of ancient Persia. Given later linguistic evidence, it is likely that an indigenous, Elamite-speaking population was living there at the end of the 4th millennium. And clearly elements from the Babylonian south must have had close, possibly adversarial contact with local peoples. But there may have been much more population movement in the area than we imagine,including early Hurrian elements and, if Whittaker (1998:111-147), Ivanov and others are correct, even
      Indo-Europeans.