You can return a role name from CPPM to CPG but you still need to map the expression in CPG.
For example, we are returning a student role from CPPM using our campus single sign on system for authentication and LDAP for authorization.
We're sending the attribute admin_privileges with a value of CPG-Brandeis-Student which assigns the operator profile of Brandeis Student. CPPM has no concept of an operator profile which is why it needs to be mapped.

