Gramps has been translated in many languages, but there is always room for more! If Gramps is not available in your native language, you can translate it yourself, and have your translation included. Translating Gramps has all the details.
The wiki could be translated, as explained in the Language policy.
What should I do if I see a translation issue? The easiest thing is to post a bug on the bug tracker. After doing that, you'll get introduced to the translators for your language and you can help them directly, or submit your own fixes.