Answer
There's no built-in framework function for this specific operation, but it's straightforward to build one: extract the current value for the target key name using the existing Client_SYS.Get_Key_Reference_Value function, then use a plain string REPLACE to swap the old key_name=old_value substring for a new key_name=new_value substring within the full key-reference string. Wrapping this pattern in a small custom PL/SQL function gives you the equivalent of the missing 'Set_Key_Reference' capability, letting you update one specific value inside a key-reference string without needing to manually rebuild the whole string by hand.