But the understanding of the language library ecosystem, or even better, your codebase, could let it execute faster and with less context usage.

That's the bit I feel you can do with ragging - keep a large library of well described solutions and then find what you need from it at runtime.

Sure but I bet this doesn't translate as well in this way to things like Erlang

<THAT'S A BINGO>

ie what everyone asking for this fails to immediately realize.

You're a bingo. It's obvious that a model could know no Python, since Python could not exist in the world in the first place.

the best llm for coding is the one that knows every programming language imagined by a caffeine-fuelled comp-sci student at 2am but never built.

if neuralink ever becomes a thing, thoughts about programming might be stolen for LLM training data lol