I am Jean-Marc Liotier. I usually choose to use software in its native English, but sometimes I want my French users to have a familiar interface and I translate some of it for them. Also I'll take opportunities to fix other translations when I randomly stumble upon bits that may benefit from my contributions.
Currently working on the French translation of the Mantis Bug Tracker : http://translatewiki.net/w/i.php?title=Special%3ATranslate&taction=translate&group=out-mantis-0-all&language=fr&limit=5000&task=view