So - as part of my efforts to get back into the habit of reading in French, I just spent 10 days reading 'Harry Potter et l'ordre du phenix'. It's a fat old book - just over 1000 pages and in my cheapo edition with already-yellowing pages the print job wasn't great so every 15 pages or so there'd be loads of blobs of ink. But it really does crack along at quite a pace - and a couple of nights I pretty much resorted to reading under the bedclothes because I couldn't bear to stop yet and the lovely man needed his beauty sleep.
As I was reading it though, I realised why I've found watching the films slightly disconcerting - although I read the first few Harry Potters in English (I was at uni, what else was there to do??? other than a new author every bloody week), I've since read them all in French - and so I've got used to the French words for things. It's a great translation when the translator keeps the allusive and punning sense of language - so in Asterix we English bods have 'Getafix' the druid (he's called Panoramix in French), Dogmatix (for Idefix) and Vitalstatistix (for Abraracourcix).
In Harry Potter there's some lovely frenchifications in the original (Malfoy anyone? and what about Voldemort?) and then some great - and some not-so-great - translations.
Great examples - swapping 'howler' for 'beuglante' is great; as is butter beer for bieraubeurre.
On the animals, swapping Scabbard for Croutard works well, and on school staff Snape becomes Rogue, and Filch becomes Rusard - both of which fit well into French but threw me a bit as I emerged blinking back into English.
Less great - Maugrey Fol Oeil is a bit clunky and literal, like 'poudre de cheminet' for floo powder loses all the fun of the Lemsip connotations.
I don't think 'chemin de traverse' works at all - but having said that, until I read that I hadn't spotted Diagon Alley - and similarly reading about 'moldus' enriched my enjoyment of 'muggles'.
And finally - a good (and old) Grauniad article about translations, and Wikipedia's pretty good on this too