spoilerrrr
Honestly, gaiona might have seen procreator kill him the first time, but lets him because of his "fatherly" love and cursed him thinking he might get to his senses. What they killed is probably what is left of gaiona. He did die, so my cannon is that he probably doesn't have the abilities he used to have. All he has are his innate powers (his soul) or what he had already casted before his first death. Having killed his soul ended everything he ever casted/created, so that is why his children had to perform a miracle to save the world from destruction.
My curiosity is more on the person/god or whatever that was seen with gaiona or who had brainwashed gaiona into thinking his children didn't love him as much as the people they cherished. Like who the heck was that and why didn't she appear ever again.
Another thing that bothered me is that none of them actually have omniciense, suposedly omniscience is to see and know evertything always, but they dont, all they know are small pieces of a possible future and the same goes for gaiona cuz somehow the literal god did not see his end coming º-º like if u think abt it technically the only character with actual omniscience would be procreator bcz his plan worked, idk man like maybe i'm wrong but it did bother me when i stopped for a second and thought about it