How do I know which MCB registers map to the standard ones from the CiA-402?

Some of the CiA registers described on this page are linked to some manufacturer specific registers implemented in the firmware of the Everest XCR/NET/CORE servo drives. You can check this exact mapping here: Register mapping CiA 402. If the register that you are looking for does not appear in this table, then the register is only implemented in the MCB.