In my experience, they're pretty poor in English too. Especially when it's ad hoc conversation where people don't finish sentences, repeat themselves, "um" and "err" etc
In the case of pronunciation this primarily poses a problem with detecting the intended word, but in other cases "cleaning up" the output may lose contextual information (e.g. what a speaker was going to say before cutting themselves off and using a different word). This is difficult enough for a human to get right, let alone a machine.
They trip up on technical jargon but handle everyday conversations just fine, including speaker detection, punctuation, idioms, etc.
But that's also a slightly different use case, where each speaker is in their own (somewhat) quiet environment and on separate connections (and thus audio tracks).
It's much harder to do all that after the fact, like with a recorded video.
I find Trint.com, which is partially automatic, to be good for that... the AI does a first pass, and a human cleans it up afterward. YouTube has a similar assisted-auto feature for their captions, minus speaker separation.