@BrianRain Smart Lighting runs locally if the devices are using local DH. If something not runs locally, that is highlighted with small print there.
There is another topic, where local execution was just discussed. New app + local processing = problem?
I don’t have two switches, but mirroring is really copying between devices. It is not working really well when it is both ways. Maybe try to build some pistons with WebCore with added debounce.