Adding MIBs to the MIB Database will not automatically add compatibility to polling your Device, and make us discover any new monitors. Adding MIBs to the MIB database will only apply in two Cases: The SNMP - User Experience Monitor and Traps.
Custom SNMP Monitor:
Custom SNMP Monitor is used to retrieve and analyze data from SNMP enabled network devices, services and applications. The SNMP - User Experience Monitor retrieves a Numeric or Textual value from an SNMP agent and then tests the value against the rules you define.
If you are receiving a Trap from this Device, and the MIB for the Trap does not exist in the Current MIB Database, it will not display the Correct Data. Updating the MIBs will resolve this issue.