I helped translating a few modified strings some months ago but I have to confess I never used the french version (like a lot of french nerds or semi-nerds, I read english fluently). So I was pretty surprised to read this post, and reinstalled MP3Tag in french tonight.
Well... there are some inconstancies. Example: sometimes "Playlist" is translated as "Liste de lecture", and sometimes it's left alone. Probably the result of several translaters ignoring each other's work (and I'm probably the one to blame for this). The best way is probably to leave it alone, since most of the french speakers are used to "playlist". A lot of english computer-related words are now part of the french language. I also saw a few spelling or grammar mistakes. But it's not unusable, far from it. And whoever did this, it's definitely not "an automatic translation made with a crappy translation software".
Maybe Doub should point to some of these strings so badly translated he deem them "crappy"? He may be a french canadian (some of them are pissed by any anglicism, anywhere)?
I agree this translation could use some polish, though. I can do it if you're not in a hurry (I'm pretty busy at work). In the meantime, you can rest assured the old translation is actually pretty good, if not perfect. And yes, I'm a native speaker.