Thanks Jean,
If I understand correctly, these proxy scripts contains the event listener function (e.g. void OnMouseUpAsButton()), and dispatch the event to FSM when get called, which is the what the "preprocess" do, adding required "event listener proxy" to the game object.
However, my FSM doesn't contains any state includes those system events (I use ray cast in the background instead of system events), which means adding those proxy script to my object does not make any sense.
So, I would say the preprocessed flag does not serve its purpose in my case, since I don't use any system event that requires preprocessing.
BTW, I found the cause why my prefabs are changed suddenly, because I deleted an unused event in event manager, which probably triggers some internal logic makes PlayMaker think it needs to reprocess all the FSMs. Could this possibly be a bug?
Cheers,
Lin