Hi there, first sorry for the confusion.
The "Wandertafel" was already mapped, there where 3 Signs and i thought the one which was mapped was a diffrent one (Verbots Hinweis Schild), my fault sorry!

I also noticed that the map which is displayed in StreetComplete...
...does not show everything.
...sync of the OSM Map delayed. 

In the future i will check twice with OSMand if there are already entrys.

Thanks for your work & have a nice day =) 