No, I know.

I'm saying the reason path abilities on profiles are listed like that is because of agenda, while also saying if it was listed like that because of UES it'd be wrong anyway. My bad if things seemed unclear.
I'm fairly certain Honkai UES won't be killed by any changes anyways.
Moon Arc Kevin SHOULD scale to anything barring Aeons given he's likely hundreds of times stronger than anything Welt does. Kevin literally statues and 3v1's Herrschers (HoFS, HoT and HoR) who would mop the floor with Welt without even using his full power. That's statue-ing people several times stronger than Welt, likely at absolute minimum.
However, big however, we don't really have anything to go off of other than vibes for this. I'm sure the above is common consensus but it isn't really provable because Kevin could be anywhere from 10x Welt to 1000x Welt... and even then, we can't prove it's the combined AP of the attacks that wiped out the universe, it could just be a unique interaction like you said.