What's the point with that quite lackluster story in Endwalker?

[Lauront]

He hated the Ancient world for valid reasons? Oh, please. We have no evidence he ever tried to change things on a wider scale in the institute he was the literal director of. Animals are stressed when they are about to be put down? That's an actually good point; so why has he seemingly never introduced methods to render them unconscious to spare them the anxiety of imminent death?

They actually had methods like that, which is shown in the sidequests. So even the other researchers were already receptive to such approaches, although obviously the ancients vary in their attitudes to the creations... and again I will stress, at no point is this concern incorporated as part of anyone's "test", be it his own or Venat's, and it's not as though the sundered somehow value all creation equally - be it raising up their own arcane servants (including egis or in Eden, primals, Sharlayan constructs, arcanima etc.), using them for a multitude of different purposes (beasts of burden, entertainment, food, etc.), or even going so far as to consume souls to power fighting techniques (reaper, necromancer.) To the extent that there was any "problem", any good he could've done would be to use his future position in the Convocation to appeal to sentiments some ancients were already open to. Rather, his problem is quite literally that they were deciding whether these beings were fit for integration into the broader star, and this caused him discomfort because it brought the concept of death in stark view. He could not understand the value of life if death comes after. You already see this when he begins discussing the will to survive with pure soulless arcane entities, i.e. lightning sprites. It then becomes apparent when he exhorts the lykaones to live even if it means hating their creators, and even if it serves no purpose for the star. There is someone who thinks like this, whose name begins with a Z. In the end, all he is really after is to validate his nihilistic sentiments by finding reasons to blame it on his broader society, which he repeats as Amon. Venat's own view is that they must find an answer to this to avoid succumbing to a loss of the will to live when purpose is extinguished. So in the end this "test" he forces on everyone has little to do with any concerns about creations and, again, he's more than happy to doom them all along with the rest of life to give himself an answer he's not even satisfied with.

And with all the dynamis in the universe she wasn't capable of twisting a single ancient. That's the density of aether you need to completely block her effects. A single unsundered. She was capable of twisting their creations just because they weren't as aetherially dense as themselves.

And even its "abundance" is at a 2:1 ratio, not a 99:1 ratio, and it is the weaker of the two. So much so that even a sundered Zodiark was able to hold her depression waves at bay for 12k years, and that it took just a few sundered to stand against the misery amassed from countless stars.