Perpetua being limited is not up for debate given the circumstances. It's not just the word "limted" was used, we have a full explanation outlining that Perpetua and Batman Who Laughs powers depleted over the course of the fight.
Let me guess, Celestials and Beyonder have never been depleted or weakened? Even pre retcon Beyonder was weakened after he erased death to the point he couldn't kill a flower.
And like I said, I haven't read A.X.E. so I'm not aware of how the Celestials are portrayed there. Could it be that Ewing's representation of them in Defenders Beyond is inconsistent with with their portrayals in A.X.E.? Sure. Could a figurative reading of "infinity" make more sense than a literal reading of it for the Celestials when accounting for it? Sure. Could Perpetua be more powerful than the Celestials? Sure.
But as far as I'm aware, this is not the case.
Because "infinity" for Celestials is literal but not for everyone else?
You're not the authority of arbitration here if you don't know.
I tend to be equally critical of all works, but not overly-critical of any. It's just a better approach to debates.
So whichever benefits the Marvel characters?
No. You're misremembering. There were two kinds of Incursions, the Red ones where the Earths collided and that were stopped by the Black Swans with bombs that blew up one of the Earths under order of Dr. Doom; and the Blue ones where the Mapmakers found a universe and then summoned the Bridgebuilders who Ã_n turn summoned the Beyonders.
Mapmakers never summoned the Beyonders, what are you talking about? I've read the entire saga multiple times, do share the scan where Beyonders destroyed a universe.
Yeah, it shattered the universe into a multiverse. Why would that make it less than universal?
The combined universe was stronger than the resultant multiverse, Ewing made it clear in Ultimates.