Sometimes, translations are not inherited

Right now, my Firefox says it wishes german, Curriki believes it can speak it so it sets the local to de_DE into the session and context. So far so good.

Everything should be displayed in German, almost nothing is. Ah well.
The rest should be in English, i.e. it should be inherited from English.

But it is not... I have many places where it shows the keyname alone, e.g join.login.title.