Adding some information, likely suggesting that multiple dimensions (infinite or not) actually exists despite Omnitraxus Prime may or may not be just
In this episode "Mathmagic", Omnitraxus Prime holds a portal at his tummy that leads Star to his pocket dimension realm where he can enter the realm with his own humanoid body and monitor various timelines by looking into the rock mirrors at "Crystal Fields of Interwoven Continuum". While "infinite timelines" can be a hyperbole, multiple timelines definitely exists. So while OP guy can have limited Clairvoyance, Alternate Future Display, Extrasensory Perception, this may not warrant universal or low multiversal level on this feat alone. He is there to advise people on space-time problems rather than an omnipotent entity by himself. But the existence of multiple timelines still mean something. I will explain later.
In
Starcrushed, OP space time guy is defeated by Toffee with Wand absorbed in the normal "hit by one energy blast and was defeated" way, not by any hax. Toffee might have used hax to absorb his powers but this is after he blasted OP out first.
And apparently space time balance remained roughly normal when Omnitraxus is stated to be in stasis
in Return to Mewni - like it is stated that Omnitraxus' job is to keep space-time in balance so his duty for keeping space-time problems answered is more like a duty.
But the ultimate whispering spell in Cleaved... Actually (at the first explosion) only the "Realm of Magic" is destroyed, along with the magic power that flows from this realm to other realms. Since the Realm of Magic creates magic powers, destruction of this realm stops magic from "existing" by not existing, therefore not available to anywhere else when magic in anywhere else is available by the stream of magic flowing from the realm of magic.
And the will of Star and Marco wishing to see each other again... they actually wished to be together forever long ago, and their wish likely affected the spell before the first spell (with several minutes of casting time and several more to kick into full effect) turns into an explosion - like if they have to input any side effects, they did it before the first explosion leading to destruction of the magic realm. And magic is only wiped out after the realm of magic stopped flowing magic out. The swirl of Starco hugging was made with Star's own powers, Marco's remaining powers with the almost empty royal magic wand, and their wish to stay together forever.
The second explosion is made by the portal, merging "Earth and Mewni".
Looks like a reconciliation is finally made...
Now... is any calculation of destruction of
Ludo's castle and the watchtower of any meaning and what would be it? Like, do they scale to anything? Also
some feats performed by Eclipsa, pulverising a robot, some trees and a small boulder that stands like a hill.