Translation contributions are handled via Transifex:
https://www.transifex.com/projects/p/bitcoin-wallet/As improvements are made in Transifex, they are eventually copied down to a new version of the app (but it takes some time).
I checked the translations you mentioned above, and they are all either (1) already translated in Transifex and waiting to be copied down to the app, or (2) untranslatable due to current software limitations. IOW, you can sign up for Transifex if you like and make a request to become a translator for Bitcoin Wallet, however there's not currently any untranslated French text.
If you're interested, here are the two translations that are pending (I've no idea if they're correct, and don't have access to change them even if I knew better):
again = de nouveau
To protect your privacy, your address will change once it receives a payment. = Par souci de confidentialité, votre adresse changera après avoir reçu un paiement.
The other three are the untranslatable ones (due to current software limitations).
I don't mean to be discouraging.... I'm sure there are other projects that would be delighted to have some help with translation. For example,
Lighthouse doesn't have any French translation yet:
https://www.transifex.com/projects/p/lighthouse-app/