When I spoke about 2-3% I spoke about preparing the "groundwork" code for this, not the translation itself. I'm somewhat confident about the estimate as I made java applications with a web front that are localized in French & English for a living. Now I'm working on the polish / spanish / French TV box that go with internet subscriptions - same translation and size issues, blablabla. However, as it has been pointed out by Draco and you it's mostly done, if not completely done.
About the translation itself, I stated above I'd be willing to make the French part. That said, I'm pretty sure you'd be able to find other volunteers around here if needed. The only question is maintaining the thing. I see 2 solutions here:
1) If you want to advertize the game as "translatable", no issue, just point out the files that Draco pointed to. The translation should, if possible, be put in the workshop as a mod.
2) If you want to advertize the game as translated, however, you'd need to ensure that someone will always be there to translate expansions, updates, and such. That's kind of a major point. I'm fan enough to be here until the release and some more time after that... but for the next 5 years ? Can't really guarantee that. Real life issues happen.
In any case, the fact that it's at least "translatable" should be in the FAQ. If Arcen wants to translate the kickstarter in other language, finding volunteers that would do the release translation mod (at least) and possibly the kickstarter translation too should, AFAIK, be doable (with a few proof-readers in case of). Arcen's choice here whether it's good or not.