You may observe the following error while importing deploy.xml and endpoint.xml into Intermediary 12.x exported from Intermediary 10.x
Unknown database or custom configuration
Details - java.lang.illegalargumentexception: agents and intermediaries
This might happen if the old version of Intermediary has a reference to DB which doesn't exist in the latest version during the upgrade. Comment out the following line from deploy.xml and try importing to a 12.x installation again:
<com.actional.sql.DBConfig key="Audit.DBConfig" name="Agents and Intermediaries" partial='true'/>
The import should work fine after removing this line.