Hi, the only player controller that exists on a client is the player controller of that client, only the server has them all. Which means you would need to call your multicasts somewhere else (e.g. the pawn), not in the player controller.
For example, if the server calls MCChar1Heal or MCChar2Heal on the servers player controller, then it will only execute those multicasts on the server, since the player controller does not exist on any client. If the server would call it on a clients player controller, then it would execute on the server and that client, but not on any of the other clients.