I'd like to point out that the "Add to cart" string has the problem mentionned for Next.
So I modified 8 lines in product.module and 1 line in product_kit.module
It's not everywhere, it's only in the submit buttons.

I haven't gotten that far as to see the same problem with other things. A lot of strings aren't translated (a good deal of them) in the french translation provided up to beta 1, used on a beta 2 install.
Hopefully the french translation team ( http://drupalfr.org ) can support ubercart as a core module for a special distribution as soon as ubercart 1.0 is out.