The Reasoning behind The Sundering? (*6.0 Endwalker Spoilers*)

[Nilroreo]

If she was so dedicated to things happening as we described them, why try to stop two necessary events?

Personally, I'm not doubting Hydaelyn's words when she says what she says. The point I was trying to make before is that the writers aren't infallible and thus are capable of accidentally retconning preestablished information across multiple expansions. When she says she attempted to save the other shards back in Heavensward, I took her at her word.

The problem arises when I'm forced to do the same in Endwalker despite conflicting information arising from everything we've learned since. Now were stuck in this awkward scenario where what she actually wanted was to selflessly spare us from prior calamities while using the 7th era as a fallback or something, all the while converting the moon into a spaceship for us to abandon our star and its remaining shards if things get too hairy (still not sure what the thought process was behind this plan), and after all this, still believe someone this righteous was willing to throw her own people under the bus without giving them a reason why for something the Allagan empire was just as if not more guilty of? There's only so many times I can take someone at their word before it just becomes noise.

[Cleretic]

all the while converting the moon into a spaceship for us to abandon our star and its remaining shards if things get too hairy (still not sure what the thought process was behind this plan)

Your post kinda falls apart after this point and I can't follow it, but I can explain this one: The moon was a big, last-ditch evacuation plan; since Meteion is focus-firing specifically on Etheirys, other planets are safe from the End of Days--and crucially, Venat knows because of Meteion that they can support life. A big, crazy escape pod.

...which was actually her Plan B. Plan A was, unbeknownst to anyone but herself, that this technology would be used in conjunction with the techniques of whatever society was actually able to get up there to learn about it (which ended up being Sharlayan) to head off to Meteion, who she'd been tracking. She hopes the world can pull that off... but if they can't, the moon is there to take them to another planet.

Which is why I point out that, if given the chance by averting their Calamity, Allag could've swung it. From what we know of Venat's real plan, Allag was capable of checking every box, they just didn't survive long enough to learn what the problem was. Hell, they were even capable of performing the specific things that we'd go on to learn were needed in Ultima Thule, provided they don't stick their foot in their mouths talking to the dragons.