Nomes de grupo não permitem letras alemãs (trema)

[GuidoD (Guido Drehsen)]

@gerhard

You are welcome to update the German translation of that error message on Transifex to make it easier for German speaking people to understand.

I did there already a couple of the german translations for Discourse in the last couple of months.
I will have a look at this specific error message on the weekend.