You can write in German, I use google translate (not very good, but I manage to understand).
I have greased both joints. I insisted especially on the shaft of the wastegate.
I have greased the wastegate joints because I had wave like acceleration - Leistungsschwankung and several times the engine was actually running like a naturally aspirated one - Leistungsverlust.
But after 1500 km the grease is not there anymore. Like it evaporated. The first 1000km the engine was GREAT. So the ceramic paste is a temporary solution.
Probably I need to use a thicker grease like LOCTITE 8008