Yes, the FSMOwner.behaviour.currentState, returns the current state of the root fsm (since .behaviour property returns that root FSM object).
What @zsoik said is correct (thanks!) You will need to first find the NestedFSMNode which is the node that actually wraps that SubFSM.
I’ve also added on the roadmap to add a method in FSMOwner to return the current state taking into account SubFSM as well.