But whose plan is it, really?
Remember that Venat had never met her successor prior to Elpis. She only recognizes you based off her signature traveler's enchantment which she applies in the future.
Likewise, you don't know who Venat is until you meet her in the future. So when Amaurot historically broke out into factions and in-fighting, you would have had no reason to pick either side. And as we know, you ultimately end up rejecting both and leaving your seat on the convocation empty. And when you meet her on the ship travelling to Sharlayan in her original form, you still don't recognize her as Venat (again, because although she's met you before, you haven't met her yet.)
When you recount the events leading up to the Final Days, Venat is the least skeptical out of the three. Her main objection to your story is that she can't understand her future actions. Would it not have been simpler to hunt down the root cause, rather than simply sit around making provisions for spaceflight so that they can all flee the star? This is why her conversation with you at the top of Elpis is critical. When she asks you to describe the beauty of the future in which you come from, and what you've set out to protect, and asks you if it's all worth it. She's not asking if your future is the right course of action. She's asking if it's the one that you believe in.
That's also what makes the scene on your return back so powerful. Everything that she's witnessed to the present day - Hyth's sacrifice to become part of Zodiark, Emet's internal suffering, the destruction of her civilization and everything she holds dear, the consequences of her sundering and the subsequent suffering and mortality of her people - all these events she has the foresight and knowledge to be able to prevent or alter. But she doesn't. Because she's chosen to believe in the future which you've told her about. Because she's chosen to believe in you, her successor. This doesn't require 4D chess. She does everything exactly as you told her she would do it all along, because of that belief, that faith. Azem's strength isn't planning, it's improvisation, and reckless optimism that it will all turn out for the best in the end.
Knowing what you know now, if you could start over, would you live your life any differently? At the end of your journey, when you look back, was it all worth it? Can you still see the beauty of life beyond its scars?
With regards to Meteion's assessment/recollection of other worlds' fates - it's worth remembering that her assessment is going to be skewed because she magnifies all of the negative emotions that she encounters, and she's more than just a passive observer. I can't remember specifically when this is, but during the latter part of the final area, someone (Raha, maybe?) notes that the destruction of many of these worlds were perhaps accelerated or even brought on by Meteion's presence. Either way, she raises a lot of really interesting questions about the origins of the Void and Voidsent.