Hmmm. Then I'm not sure where it was. As I do remember getting said impression from someone's reaction to the pre- sundered new life as not being what they were expecting. Kind of like how if you baked something and it didn't come out as you hoped it would all due to you having accidentally over aerating the batter. You parsed the rest correctly. As what we get shown are the Ancients able to create things that wouldn't be at seed or seedling level.
That if the reason for the need of cultivation was only due to their thinness in aether then why did Zodiark make them thin in the 1st place? You wouldn't need to cultivate as much if you started with something thicker. Like plants some you can transplant either from plug-ins or transplant after they've grown some from seed. Meanwhile things like your root vegetables don't really transplant at all if you have to well uproot them so that others can go and plant them in their garden.
And yet one would think Zodiark should be able to at least do more than pop out something that had such thin aetheric density. Unless as I said the reason why was because they didn't think to make it be thicker than their normal creations. Or if they did think and try to make the new life as thick in aether as the ancients themselves, but they ended up regular creation thin then maybe there was a problem. Which we wouldn't know about as time and well plot didn't get to see if the thin aether density was accidental or not.