Though it's probably long past it's due and thus no longer on their radar (though they could have done it along with the other ARR reworks mid-Shadowbringers) they should have split Ultima Weapon off from Praetorium as it's own trial.
This would have the Praetorium raid ending with Gaius as the final boss, and be a similar length to Castrum, Then both duties would have the same rewards.