[rschiks]

Then probably I'm going to be different. I don't think it's wise to use a language tag as a distinguisher. Just mark it as a different art type and return it like one.

Since it the two main artwork providers are handle it equal the same, i thought it would be the simplest and easiest way (to get the difference over api).

That would be the easiest, I agree. However, currently I don’t threat it differently. If I need to go through all the posters and change the language tag for the animatedkeyart to none, I can rather do it right and introduce the new artwork type and mark it as animatedkeyart.
Future proof