In French, I have seen it make the same conjugation mistakes as native speakers ("elle a terminée") as well as a few gender mistakes on conjugation (not sure which one exactly anymore, but something like "le lutin est tombée") which wouldn't be common for native speakers.
But it is very good, I have been using it to translate Dutch children's songs into French and that works great, it's quite lousy at counting syllables but very good at finding equivalents for expressions that are not directly translatable.
It can even invent words when asked to, a friend has been struggling to find a good translation for Lovecraft's "night-gaunts" for some time (the traditional translation is "maigres bêtes de la nuit" which is good, but didn't really work for poetry as it's much longer) and ChatGPT was able to suggest portmanteau words that were interesting, and other rather good neologisms that looked like regular French words, based on two Greek or Latin words.