I would say they came much closer than Lahabrea, who died still in disbelief that his Perfect Plans were flawed. Elidibus certainly expressed doubt near the end, and I'm quite certain Emet-Selch's last words were an admittance that his plans had failed, so he needed to at least go out with something worthwhile in the short time he had before dissipating.
I see this as an extension of the primary message FFXIV has throughout its entire story arc: that life is painful and difficult, and we can never know the truth for certain, and we will make mistakes that have repercussions beyond ourselves, but for all of that, we must still live on. It was a little subdued in ARR, but definitely slammed into our faces in Heavensward and Stormblood.
So the characters who had absolute certainty that they were right has always had that faith questioned, and whether they admit to doubt and retrospection is the divide between hero and villain. Which doesn't even mean they have to change their actions: Estinien knows that his nation is built on a lie, and humans and dragons can live together in peace, but that doesn't mean his duty of slaying (or at least permanently stopping) Nidhogg has changed.
So I can see where Venat and the Convocation both come from: both had very limited time and information to work with, and both needed to make a decision now (albeit at different times for different reasons). The difference, in my view, is that the Unsundered became rigid in their dogma, where their way must be the one way and no other, to the detriment of their own fellows in the Sundered Convocation.
Meanwhile, Venat via Hydaelyn has expressed humility and contrition, while still also believing that what she needed to do hasn't changed. She accepts that she could be wrong, but absent any convincing evidence of such, she remains on her course.
So everyone, from Alphinaud to Fordola to Hraesvelgr to Hydaelyn, need to accept that choices are necessarily made without perfect knowledge, and so these choices may be the wrong choices. But the choices need to be made nevertheless, and if it turns out to be wrong, to accept the consequences thereof. Alphinaud and Fordola never demanded forgiveness from those they wronged, only humbly asking for it. If no forgiveness was given, they just had to live with that.
And that is, in the message of FFXIV, simply life.