Hi Bananapan,
I am not sure if everything went correct here. You tagged the relation of the 2 Schlossbau building parts as amenity=shelter. I assume something different was the purpose. The combination of these 2 buildings can be named Schlossbau, not Altan. Altan may be the lower one of these two building parts.

Can you please review this one more time?

Thanks,

Redd