I contribute on SUMO and i wanna know how i will help to fix better the Greek language in 43.0.4
the best way to get in touch with the Greek community is on their mailing list, https://groups.google.com/forum/#!forum/mozilla.community.greece.
To contribute to l10n, they’re working on pontoon. You’ve started there already? For desktop, the project is https://pontoon.mozilla.org/el/firefox-aurora/.