I have not translated a game myself, but from what I know of the language variants in Quest, you'd have to have two separate games if you want to use the language scheme in Quest. For example, at the top of a game file is typically an include for "English.aslx", which could be changed to Deutsch.aslx. But it's a compile time thing.
I threw in the qualifier "if you want to use the language scheme in Quest" because you could always roll your own language switching scheme. I'm not sure what that would entail, but it would probably require touching all the places that use a template and making it select based on language (somehow). Not a piece of cake, but not impossible if you were so motivated.