> Or translate it from their first language if that is not the common language of the forum in question.

While LLM-based translations might have their own specific and recognizable style (I'm not sure), it's distinct from the typical output you get when you just have an LLM write text from scratch. I'm often using LLM translations, and I've never seen it introduce patterns like "it's not x, it's y" when that wasn't in the source.