Notes:
When you Consume a two-way WebServices in BizTalk, it's recommand that set the Response Message to XMLDocument type and then handle this Back response Message, you can handle it based on the MessageType, if a SOAPFault present, it should be "http://schemas.xmlsoap.org/soap/envelope/#Fault".
You can also add Exception Handle to catch the SOAPExceptions, but this will do nonuse for the SOAPExceptions raised by the Services the orchestration consumed. Gernally, BizTalk will catch SOAPException raised by the adapter,This allows catching any custom WCF faults and handling them gracefully. It also handles general SOAP exceptions but the downside is that SOAP exception caught will not be original SOAP fault that came over the wire from the service. It’s going to be secondary SOAP exception thrown by the adapter. Receive pipeline will try to match incoming message type using XPath expressions defined in the send port configuration.