Thank you guys for your suggestions and help.
The noSOAPMakeSysErrFromResponseFault Parameter didn't solve it.
I suppose the problem was the SOAP 1.2 response.
Changing SOAP Receiver CC to "No Use SOAP Header" , XMBWS.NoSOAPIgnoreStatusCode Module-Parameter and handling the Messages with a XSLT mapping solved it so far.
Now the fault message runs into the adapter engine and is handled as regular response by the mapping.
(fault reason regular error response in target system)