Did Zodiark ever do anything wrong?

[Cleretic]

I believe we actually knew since Ultima Thule. When we spoke to the ea about the Final Days they said the same calamity had hit them. Alphinaud even pointed out to Meteion that the Meteia inadvertently drove worlds to their doom. So we knew from very early on that the main plan was the only chance, the backup was doomed to failure before it was even conceived given that the ea's planet, Deneb III, was only the third star visited by the Meteia and even then they were already spreading their despair.

Deneb III isn't suggested to be the Ea's home planet, nor was it clear if it got hit by the same thing exactly or just a similar phenomena; the Ea only bring it up as 'hey something similar happened over here'. The Ea only being the third planet Meteion visited even suggests it might be an unrelated phenomena if you assume that the Ea haven't really updated their knowledge of the universe, since it would've happened beforehand, but I don't think that's true; the Omicron definitely seem capable of seeing outside Ultima Thule and updating their knowledge.

Hell, my assumption now is actually that Deneb III was a Mandervillian planet. While we know that not every star a Meteion visited reached the same fate as ours, the Mandervillians absolutely got hit by the same despair-pocalypse as we did.

[Iscah]

I will say though that hydealyns back up plan was pure madness. Shove a bunch of frightened people onto a ship where the slightest extreme emotion would result in them transforming into beasts... what would be more stressfull or emotional that fleeing the planet? IMO the moment that shop left Zodiarks influence they all would have turned.

Everyone already "left Zodiark's influence" the moment we killed him on the moon. That's what allowed the Final Days to start up again.

Anyway, I'm not certain whether Hydaelyn's stated evacuation plan actually was the plan, or just what she told the Sharlayans to get them to start building a spacecraft that was actually capable of travelling much further than the moon, without actually mentioning anything about Meteion.

Deneb III isn't suggested to be the Ea's home planet

The Ea mention two planets, both of which sound like they could be their home, but it seems strange one way or another.

This quest mentions a different planet called Sadr IV in a way that indicates this is a planet whose orbits they use to measure time by, which could be an astronomical observation of a distant planet or it could just be an overly technical way of saying "a year", i.e. the time it takes for their home planet to complete an orbit.

Meanwhile Deneb III is mentioned here as a place that the Ea observed to be affected by the Final Days, likely from start to end. So is it their own planet, or is it one they observed from afar before Meteion destroyed them as well, but these recreations are unaware of that later history? Perhaps it was the very first, making it an isolated incident to the Ea's awareness, with their own doom not far behind.

The lorebook doesn't mention their home star either way.

[Dikatis]

The Ea mention two planets, both of which sound like they could be their home, but it seems strange one way or another.

I don't think the Ea experienced the Final Days. The Ea's home is designated as Ostrakon Tria in Meteion's report, and this is what she had to say about them:

Tria: Evidence of large population centers akin to cities recovered. No extant life-forms found — only their lingering essence.

One race had concluded that finite time was the root of all woes. Aspiring to shatter its shackles, they went in search of infinity. They discovered nothing is infinite, and that neither time or death can be cheated. Disillusioned, they gave up on the future — and themselves.

The Ea had already discovered the inevitable heat death of the universe and had exterminated themselves via exsanguination of their aether before Meteion got there. She presumably got information on them via an Echo-adjacent power and her own abiltiy to tap into the emotions of others.

[Iscah]

Tria: Evidence of large population centers akin to cities recovered. No extant life-forms found — only their lingering essence.

The Ea had already discovered the inevitable heat death of the universe and had exterminated themselves via exsanguination of their aether before Meteion got there. She presumably got information on them via an Echo-adjacent power and her own abiltiy to tap into the emotions of others.

It's also possible that what Meteion classifies as a "lingering essence" of long-dead inhabitants is literally what the Ea are in the form we encounter them. They shed their living forms long ago so Meteion does not detect them as such, but she still might have directly interacted with their incorporeal selves.