All currently-unknown real languages that an LLM might decode are languages that are unknown because of a lack of data, due the civilization being dead. An LLM won't necessarily be able to overcome that.
In the book the characters had access to effectively unbounded input since it was a live civilization generating the data, plus they had reference to at least some video, and... something else that would be very useful for decoding language but would constitute probably a medium-grade spoiler if I shared, so there's another relevant difference.
Still, it should also be said it wasn't literally LLMs, it was humans, merely, "affected" in a way that they are basically all idiot savants on the particular topic of language acquisition.
Oh, yeah; I'm just not convinced there's any particular reason to think that LLMs would be useful for decoding languages.
(That said it would be an interesting _experiment_, if a little hard to set up; you'd need a live language which hadn't made it into the LLM's training set at all, so you'd probably need to purpose-train an LLM...)
LLMs are.. not bad at finding some semantic relationships between some arbitrary data. Sure, if you dump an unknown language into LLM then you can only receive a semantically correct sentences of unknown meaning, but as you start to decode the language itself it would be way easier to find the relationships there, if not just outright replacing the terms with a translated ones.
In the book the characters had access to effectively unbounded input since it was a live civilization generating the data, plus they had reference to at least some video, and... something else that would be very useful for decoding language but would constitute probably a medium-grade spoiler if I shared, so there's another relevant difference.
Still, it should also be said it wasn't literally LLMs, it was humans, merely, "affected" in a way that they are basically all idiot savants on the particular topic of language acquisition.