I'll have to add translation support to the framework first. I already finished the generation of templates, so you can still get to work:
Download the translation template I just added as separate file, and use any text editor to replace each null entry with a french line of text in quotes, matching the English line above it. Do not modify anything else! It is important that the result remains a valid JSON file with the correct structure and unchanged English lines.
Once you are done, send me the resulting text and a short note how you want to get credited. I also accept translations in any other game language supported by the vanilla game, if somebody else is also interested in translating!