first guardians are only described as being Nearly omnipotent
Once we’re made aware of their limitations, the description does change to ‘virtually omnipotent’ most of the time, but from time to time they’re always talked about as ‘Omnipotent’. John calls Jade ‘Semipotent’ and I think that’s the best way to describe it. Lord English is described by Scratch as ‘considerably more powerful’ but not even then does he say he’s ‘truly omnipotent’.
Even the Horrorterrors are described as being Omnipotent and Omniscient- Deities they are, but given English is sort of slaughtering them even this Omnipotence is not true. And Skaia is more Omniscient than Omnipotent, so, yeah. Hell- Even the AUTHOR dies, in a way you could say Homestuck is all about how Omnipotence doesn’t mean anything when everyone is a God.