See, there's a lot of nuance in German.

There is no equivalence between most dairy products between Germany and the English-speaking world. Most terms are just untranslatable because they refer to similar but slightly different concepts.

There is fresh white spreadable cheese ("Frischkäse"), but it's savoury, not sweet, and less fatty than American-style cream cheese. You certainly wouldn't use it to frost a cake. If you spread Frischkäse on a sandwich and handed it to someone as a "cheese sandwich", they would probably be a bit surprised but accept it as a cheese sandwich.

But Frischkäse doesn't go in Käsekuchen. Maybe my description of Quark was misleading, but it is terribly hard to describe since it literally just does not have any equivalent product in the US. Imagine describing marshmallow fluff or root beer to a European.