I was recently tinkering with something on a tangentially related topic out of curiosity, and learned a bit about how LLMs “translate” that might help shed some light on the subject for you.
Specifically, after a recent trip to Rome, I’ve been reading (and re-reading) some history. I noticed that the same source material happened to be covered in two of the books, but the Latin was translated slightly differently. Obviously, translators always have some discretion; there’s no such thing as a “pure” rendering from one language to another, because languages don’t map directly onto one another, so the translator is obligated to make interpretive choices, trying to convey the sense of the original text.
In any case, to make a long story short, I started fiddling with chatbot translations from Latin to English (using ChatGPT, Gemini, and Grok, to compare the outputs). I asked the 'bots to include parallel or embedded annotations about subjective interpretation, why each one it thought its chosen rendering was favorable, and other possible translation options.
But where it got really interesting was when, again out of curiosity, I started asking for English-language texts to be translated to Classical Latin. One of the 'bots (I don’t remember which) included some caveats, where it said this task was challenging, and cautioning me against relying on the output. I dug into this a bit, and based on the responses, I asked similar questions of the other 'bots. When confronted directly, they all confirmed the difficulty of the task, on the same basis.
What is that, specifically? It’s the fact that there’s a very large corpus of Latin-to-English translations, but an almost nonexistent corpus of original English writing having been translated to Classical Latin. And if you think about it, that makes perfect sense. Lots of English speakers want to read, say, Cicero, or Plutarch, and there’s no shortage of alternative translations to choose from. But basically nobody wants to read, say, John Grisham in Classical Latin. So there’s essentially zero material to provide translation references in that direction.
And that exposes something really fundamental about the way the LLMs “translate.” They don’t “understand” either language, in the sense of rendering meaning from one to the other. Instead, they have a big statistical model which supports probabalistic transformation. When it sees “Romani ite domum,” it has enough comparative examples of how that phrase is rendered to English to derive the translation “Romans go home.” But it doesn’t know that “Romani” means “Romans,” it doesn’t know that “ite” is imperative, etc etc. Instead, it’s able to map the Latin to English because it has lots and lots and lots of references that allow it to model the transformation.
Comparatively, though, it has no meaningful corpus to model the transformation the other way. If you give it a sample of English text that has never been translated to Latin (say, “It is a truth universally acknowledged…”), it will take a stab at it, making its best guess, and the output will probably be reasonably comprehensible to a Latin reader. But will it be good Latin? Will it have been translated in any meaningful sense? No, not really, for (I hope) obvious reasons.
Go ahead, try it yourself. Ask the 'bots about translating from Latin to English, and the other way around. Ask them to explain why the former is easy and the latter is hard. Take a short English excerpt like the Austen above and ask the 'bot to render it in Latin, including annotations about challenging phrases and alternative renderings. It will become quite clear, very quickly, how the 'bots are actually handling this kind of task, under the hood, and why an English-to-Latin translation request is so difficult, just from the standpoint of a system that requires a significant foundation of training references to construct its predictive model. (And this is completely aside from the subjectivity involved in translating to Latin specifically, with its moods and other expressive forms that require the writer to know what they’re trying to say.)
Anyway, I thought this was an interesting insight into the operation of these LLMs, which I think makes obvious why they would be essentially helpless trying to work on a “dead” language that has no existing translation references.