Inconsistencies with the sundering (Spoilers)

[PeaTearGriffin]

So, why do you think those who couldn't wait for that to happen on its own would be willing to wait for enough aether or whatever they ended up using to send a group of people, or familiars, or creations to go fight something they don't know how to fight?

Because some ancients might see or can be convinced that its better to solve the root of the problem instead of just applying a band-aid solution like zodiark. Venat certainly saw that it was necessary to fight the root of the problem which is partly the reason why she sundered everyone. Also there's the possibility that gathering the aether might not take that long.

I'll dive a little bit into what I think could've happened. This is just a fan theory so don't take this too seriously. Venat could put a plan into action that involves informing the other ancients of what she learned from her encounter with meteion and hermes WITHOUT implicating hermes. She could say: "Look, your memory is gone but mine isn't. Your creation went crazy and escaped and is coming back to kill us all and we need to do something." All the while she could tiptoe around the fact that hermes attacked her, emet, hythlodaeus, and the WoL at Ktisis Hyperboreia. Why avoid revealing this to hermes? Because they need hermes' cooperation because he knows the most about meteion. Would the revelation that all the ancients might die to hermes' creation cause panic and mass hysteria? It might and it probably will. But that doesn't mean the ancients will refuse or are incapable of a devising a plan to fight meteion. Once the hysteria subsides they can begin working on a plan to travel to the edge of the universe and kill meteion.

In the event that it does take lots of time to prepare for an assault on meteion I'd imagine there would be a lot more resistance to carrying out such a plan, so venat would have to sway public opinion. She would have to convince everyone into taking a course of action that resolves the problem at the source (killing meteion) instead of just a band-aid solution that is zodiark's aether shield. Will it be hard to convince all the ancients that this is a plan worth putting into action? Yes. Will it be impossible? No.

Or Hermes in a "Hey Jackrabbit you got us into this mess now go deal with your pet project"? Or do you not even think about taking said risk because they one or both could choose to sabotage the mission even if you saw it as a suicide mission.

If hermes were to join the expedition to the edge of the universe only to betray the entire crew, that would in my opinion make for a very entertaining cutscene. It would almost be like Cypher from the Matrix where he betrays morpheus and everyone on the ship.

The other thing is would they i.e convocation and any general public choose to want to use Zodiark to speed up the process and thusly condemning even more souls to live inside it?

If it's to eliminate something that's a threat to their entire civilization, yes possibly. Desperate times call for desperate measures. If someone had a chance to sacrifice themselves to zodiark in order to save everyone on the star, I'd say that's something that the ancients might find worth celebrating too.