Instigator Local triggers are convenient for setting up buttons or world items that only some people can see, but it is currently impossible to limit this behavior based on owner or master player types. Since all the currently available Owner and Master triggers are broadcasted by default, any actions executed in those triggers will be seen by everyone.
A simple use case for this is a button that only appears for the room master. Ideally, you would set up an OnEnable MasterLocal trigger in your world that shows the button only for the master, but right now that is currently impossible. Setting the trigger to Local will have it activate for everyone because they all observe the OnEnable event. Setting it to any of the current Master types will simply broadcast the enable event to everyone in the room.
As a result, I would like to see OwnerLocal and MasterLocal type triggers added to the trigger system. This would also bring the trigger system up to parity with the SendRPC event which already supports these as target types.