Continuing the discussion from Please replace German umlauts in URLs with their respective digraphs:
I love this feature a lot, thanks to @gerhard at this point! But (there is always a but…) I just saw, that umlauts aren’t handled correct in the bagde urls. That isn’t a big deal, but I think if we do it, we can do it also for the badges. Don’t know if that is hard to implement. Maybe a feature for some time in the future.
Thanks for the praise, but (yes, there’s always a “but” ;-)) most of the work was actually done by @fantasticfears.
Thanks for clearing this up @gerhard. We say: “Ehre wem Ehre gebührt.” 
Okay, maybe @fantasticfears will find some spare time to make that Feature perfect. But as I said, it is a small little thing…
Well. My PR is not relevant to language any more.
You can find a setting slug_genertaion_method controls the slug things.
Now ascii is the default which means we are using Rails default slug generation algorithm. So it’s up to you to update the transliteration rules…
Hope it explains things.
The German transliteration rules should be fine. I didn’t verify it yet, but I think the problem is that badge URLs do not use the slug_generation_method.
Confirmed that.
Badge can be a English name. For the default badges, translation will be used if exists. But it requires you uses the default English badge name.