Good news everyone! I have enchanted item cooldown working. It's pegged to four seconds for now, which seems arbitrarily reasonable.
Still concerned about enchanting. I just tried to make a ring of invisibility, and the charge cost is slightly less than the magicka cost of the same spell. With my indispensible cast cost reducer mod, it works out about the same, yet the charge reservoir in the puny ring is larger than my magicka pool. Injustice! I'm considering making everything 2x or 3x charge use (as long as it doesn't break any pre-existing items). Need to review every magic item, again.
Also noticed enchanting scrolls with an NPC costs the same as if it were a normal reusable item... that needs to change.
Great news!
I agree that enchanted items' cooldown should be greater than the casting time for spells. Four seconds seems good to me.