After distributing this config the strange thing is, that the Multisite Configuration doesn't appear in the Webinterface on any SH.
If I add the multisite CM manually the error from above is popping up, and I cant search my data.
Second strange behaviour is that, when adding the SearchPeers themselve, without a CM, the data is searchable without any problem. Looks like the config isnt pulled.
Otherwise every conneciton works fine: IDXC-Singlesite -> CM Singlesite, IDXC-Multisite -> CM Multisite, and every instance is connected to a central Monitoring Console.
I read about a similiar problem in a question already asked, but the offered solution didnt help.