I don't think LLMs are anything human language specific, so would they really shine here? I.e, COBOL and SQL may be great for humans who otherwise aren't used to programming languages, but LLMs have seen everything, and thus are able to know any (programming) language, not just ones which are English-like.
I think it would shine because COBOL is very verbose and the programs written with it (batch jobs) very straightforward but also very boilerplate-rish and boring to write by hand, a situation with little risk and high reward to automate.