We have maintained the roles correctly and manually for the READ RFC user, but in step "Check Configuration" of Managed System Configuration, the activity "Configuration Check" is in red status due to the error "Role has not been granted to Read RFC user SM_XXXCLNTXXX_READ".
You are having this error because assigned role is not directly copied from the SAP standard role.
To resolve this error please do as following:
For SP10 and SP11, go to solman_workcenter-->Tab "SAP Solution Manager Administration"-->Users-->Tab "Managed Systems"-->Use the filter to search for the Standard ID SM_XXX-->Choose the correct managed system-->Mark the checkbox "Accept manually created user without checking role assignments" for the READ RFC user.
For SP12, go to the step "Maintain RFCs" of Managed System Configuration, mark checkbox "Accept manually created user without checking role assignments" for the read RFC user.