Forgive my naive understanding of LLMs - but how do you get semantic understanding of a codebase, such that it knows what changes to make/why/where, without a wider understanding of language more broadly?

I'm using the word understanding loosely there, but I couldn't think of another word.

It's a totally fair question. I'm personally wondering if there's a half way point. Some kind of structured language that isn't plain English that a "dumb" LLM is able to parse. It could be human written, or it could be written by a "smart" LLM at a greater cost.