Hey there
i know your aren't that's the reason why i wanna tell you, it's just an opinion i never wanted to make you angry or something like that
Drachenpriester = Dragonpriest is totally right, it's just the name of the faction.
It's the Reich of the Dragon, so it's called Reich des DrachENS
the ending changes because of the "ownership" of the dragon
It would be also possible to name it Drachenreich, but if you named it Reich des... you need the ENS as ending
In German it is sometimes a little bit tricky, so i've thougt you might want to know it. as i've allready written in the first post, a german totally understand what you mean, it's just the wrong ending.
The Troops and so on are all right in the name: Drachenkavallerie, Drachenpriester, Drachenusw. it's really just because of the Reich des... what caused that you need an other form of the word