Wikimedia currently do not allow this, blocking any new projects for Latin, Sanskrit and Classical Chinese; and stopping Ancient Greek entirely, excepting Wikisource archives.
The policy comes from the Language Committee (LangCom) and is 14 years old. In that time, volunteers in the Ancient Greek Wikipedia test project, at the “incubator”, have tried to lift the ban four times, each unsuccessfully.
The ban is in place supposedly because all Ancient Languages “lack native speakers”. This is of course true – it is a fact of life that they lack native speakers. But the conclusion the Committee has come to, that it is therefore impossible for Classical language projects to find readers, share information, or be written accurately, is far fetched.
Latin, for instance, has had no native speakers for perhaps 1400 years, while Sanskrit has had none for around 2000 years. Yet the periods after losing their native speakers have been the most productive.
The Latin corpus is estimated to contain just 0.01% of material from the time it was a native language, while 99.99% of what is extant comes from the medieval, renaissance and modern periods, where it was a working second language, native to none.
Under Wikimedia’s current policy, Latin writers would have been banned from writing a Wikipedia while it was the leading language in Europe for science, theology, education and literature. Erasmus, Thomas More and Newton would have been told to get lost. The same would be true for Sanskrit and Classical Chinese contributors, but more so, over longer periods.
Classical languages have evolved methods to deal with questions of idiom, although it is of course an additional difficulty when learning these languages. Arguably, they also have reduced idioms, lacking for instance many informal registers, dialects and so on, in their highly fixed forms. In some cases those fixed forms may not even correspond to the original spoken language.
In this Classical languages share a lot with “constructed languages”, which are permitted by Wikimedia’s Language Committee. They may in some cases, be regarded as partially constructed. They serve the same function as a common second language. Classical languages are the direct inspiration for constructed languages.
Will Wikimedia place Latin and Ancient Greek on an equal footing with Volapük? Will Sanskrit and Classical Chinese be recognised as languages with significant contemporary usage? Will the cultural sensitivities of religion and belief surrounding these languages be understood?
That all remains to be seen.