JAC
Sorry for the late reply and thanks 🙂.
Our community is very happy with the forum, so Kudos to Flarum! A few featues still missing for us, but nothing to be worried about.
We do use Linguist by FriendsOfFlarum and of course the language packages @Justoverclock mentioned.
However Linguist, also already mentioned, won't translate the posts, but at least the Flarum core and most extensions (we have quite a lot I assume).
If you need some exchange on great extensions for a football forum, you can find me here (flarum discord).