Hi,
Please try this.
1. Go to the UME and check what UME roles are assigned to SAP_XI_APPL_SERV_USER.
2. Mapped those UME roles you get in step 1 to the newly created custom role Z_PI_ APPL_SERV_USER.
Though the role is in ABAP side of the system, these sap standard roles have appropriate objects representation in the Java Stack. When creating custom PI/XI SAP standard roles, you also need to copy the objects from it's Java Stack.
Thanks, hope it helps.
Regards,
Santi.