No, it’s not a thing…I just happened to have access to a DVD of a couple of the Harry Potter films in French. It was quite an experience I’ll tell you.
I was originally going to watch Harry Potter and the Half Blood Prince, but the moment it came on, I remembered that I watched it in English just a couple of weeks ago. Instead I opted for the Order of the Phoenix (because my only other option of the Goblet of Fire wasn’t in any of the cases).
It was a very well dubbed film. For a vast majority of the time I couldn’t really see any issues with the syncing of words/mouth movements. I don’t know if being French (or being fluent in French) would have affected that at all. It’s probably easier to pick up issues with your own language syncing than someone else’s.
One thing that really worked well, though, was the voices they chose. Sometimes the dubbed voice choice isn’t a good one and that just makes it laughable. But the voices fit the characters enough. For example, Bellatrix Lestrange was really high pitched and screeching which really fit the scene/character well. The voice of Harry and the other main characters were so good that I barely even noticed that they were dubbed. I just got lost in the story.
There’s something really enjoyable about watching films in another language, or at least dubbed in another language (with subtitles) or listening to music in another language. I’m not sure what it is, it just feels like something else entirely.