The questions I want EW to answer the most: WHY and HOW was the world sundered?

[Yuella]

No, Hydaelyn was summoned to stop the Darkness (the Sound), just like Zodiark. Emet and the Ascians are sensitive snowflakes who thinks Hydaelyn's summoners are out to get him and Zodiark. (Emet is an unrealiable narrator, so is Hythlodaeus' shade, who was created by Emet). The difference is Zodiark only temporarily prevented the Darkness. Hydaelyn was meant to be a permanent solution (as long as the Ascians didn't do any rejoining). Unfortunately, the Ascians keep doing rejoining and while it's bringing Zodiark back, it also threatens to bring back the Darkness.

Refer to my previous post

https://forum.square-enix.com/ffxiv/...=1#post5689000

especially this



Whenever Minfilia (3.2) and Venat (5.2) talked about Darkness, they're talking about the Sound, not Zodiark

Venat's cutscene is the most objective of them all.
Minfilia talked directly to us (3.2), she could be lying or wrong
Emet talked directly to us (Qitana Ravel), he could be lying or wrong
Hythlodaeus talked directly to us (Amaurot), he could be lying or wrong

Venat didn't talk directly to us, it was a recording of their group preparing to summon Hydaelyn.