I fully agree. I'm Swedish and have recently used GPT to help me draft some cover letters in Swedish. Even with all the mandatory personality tweaks and prompting, it always seems to default to highly florid and self-congratulatory Americanisms if I'm not careful. It's very subtle.

I do understand where proponents of language equivalency are coming from. LLMs seem to be extremely good at answering simple, one-shot type questions and mechanical 'low-level' translations for most languages. I feel like as soon as you introduce complex chains of thought or multi-step cross-linguistic tasks, minor imperfections stack and become magnified, just as with coding tasks or context rot.