Current-best models are pretty fluent at major languages and cultures, so it's untrue at least for the "any" qualifier. Performance is barely affected or might be even better sometimes. However English patterns can subtly leak into native patterns of other languages. It's obviously very different for low-resource languages, but to improve them you need more data, not a new model.

>Current-best models are pretty fluent at major languages and cultures

strong disagree on that one. As a German interacting with ChatGPT, even in German it gives me the feeling of talking to the Pluribus people, which reminds me of an anecdote of Walmart failing in Germany because people were freaked out by the constantly upbeat, smiling employees.

Understanding a culture is a very different task than translating the syntax of a text, and these systems might be capable of syntactic fluency but they do not really understand culture. You have to metaphorically abuse these models until they stop sounding like the crossover of a HR department person and a Mormon missionary