[Ohverride]

Casting fortuna sometimes(?) puts your spells on complete GCDE as opposed to 1s GCD.

Just lyk this isn't complete GCDE, it's just a very short GCD. As another Fortuna user if you try to spam it as if it were GCDE, it doesn't work. I think instead of caster it's caster ultima. (You can also see the icons temporarily darken when you use abilities it's simply very swift.)

Isn't very short GCD what GCDE is?

Most GCDE spells have a very small delay in between casts.

No, GCDE is no GCD. I use GCDE spells like plasma leap to confirm. If you use a spell like plasma leap, there's no observable GCD. If you use a fortuna spell with the aura buff, there is, but it's very short.