Do we know if the Periodic Event is accurate/constant? It looks a bit random in my case, and I really don't know why.
Do we know how Attach Unit To Region works? I ran it once, at map init, and I suspect it to create a bunch of bugs all around, as if the region was moved through all the map to find the unit.

Periodic event is bound to be a bit erratic, due to timing errors with in the engine due to lag or some other things, but the difference should only be slight. Have you noticed anything huge related to timing errors with the event?

Yup.
The system is supposed to spawn a Power-Up every 15 seconds and remove all other PU once it is spawned, I remember it spawning after like 20 seconds and disappearing right after it (like 1 second later).
I've also noticed that some times, when a PU spawns near a CPU, my Idle trigger is activated. And if a CPU blinks, the PU are removed. This makes no sense.

Make sure you are using real time and not game time.