I think you're missunderstanding what isEnergized is for, isEnergized is true when a rune becomes ready throguh one of three methods:
Blood Tap,
Runic Empowerment or
Empower Rune Weapon. So it will never be true when you just spam rune abilities, what makes it weird and hard for me to get an idea what to do is that GetRuneCooldown() still returns the cooldown the rune should've had if it was energized.
But I'm gonna do some testing with the help of that script.