@Kuraiaku
We have no proof of their existence. There haven't been literal floating islands or demon lords in our world as far as I have checked nor has anything supernatural been confirmed.
We can't punish people that we don't know exist.
But the author of a story certainly can.
As someone that also writes a lot I can see the merit of having someone get away unpunished, but this really wasn't that kind of story. Every loose end in it was tied up... except the one regarding the Goddess incompetence, instead the offsprings of the old royal family, descendants that likely never had anything to do with the evil actions of the king and the surrounding nobility.
They had to be punished and never see anything outside of the church until death, but the Goddess gets away scot free? If they traded places and the Goddess took her place, it might have been somewhat of a redemption for the Goddess.
Instead the story ends on good notes... but with an ugly loose end alongside it.