global enchantments when there are 5 already?

[Ygorl]

The first global cast takes the empty slots. Any others are treated exactly as though there were five globals already up (since there are!)

I think the order in which ritual spells (including globals) happen is the order of unit ID (which might be the order in which units were created, and almost certainly is the order in which they show up in the commander list in a province) or else that order reversed, with a 50% chance for either.