which language in ingame Bug Report?
If you don’t get an answer here, you could always ask CS or maybe (I’m not sure) the forum Mods would know. Though, I’m guessing, since CS reports can be delivered in German, the in-game reports can, as well. =)
you mean, write a ticket asking which language to use?
There’s a german forum for gw2 so I suppose there’s also a german support
I’d keep reporting in german