I chalked that up to 'God is Omnipotent and Omniscient within his/her realm', since that is basically the narrative of most religions. Higher tier capability allows for higher tier magicking around wards. Honestly, there are too many unknowns about magical mechanics to even bother trying to identify what is and is not possible.
I don't want to get bogged down on stuff here, so I just want to point out that you kind of made an assumption, here, that doesn't really hold in the face of either the canon material nor this story in specific.
If Being X were omnipotent and more importantly omniscient, he would never have allowed the whole Tanya thing to play out in the first place. This literally happened due to Being X's lacking the power to compel worship, and the lack of insight into human minds to know better than following his strategy to get faith. He's also not the only god of that setting.
Furthermore: in my narrative, I've never really brought up deity-type beings outside of the Lovecraftian model, but I've also never really shown "separate rules for separate places". Any physics or magics Andes has encountered have worked everywhere he's been.
Lastly: his wards were actually able to fight off a local omnipotence like you describe, before: the Isekai 'Verse System. (And technically the Angel when it was invoking it's god, but that's... shenanigans.)
So... I'm not sure where you got that impression from, but it is not helpful to understand just how
wrong what just happened in my story is.
This is a hint:
something is wrong with this picture.
This makes sense for the story; However, keep in mind that our MC already knows that Magic works differently in different realms.
I'm not saying that what happened didn't make sense - it completely does. But next time (if there is one) he should have a realization that maybe the base magic mechanics don't always match up. (In this case, no pushback against his wards)
Just to reaffirm: that's contrary to how I've shown things to work in this story. Especially with eldritch necromancy -- I've expressly mentioned, I believe, the fact that Dho-Na effects actively impose their rules on the local substrate. This is why the Tuning Forks and Dho-Na Banishment effects were able to be hybridized for the weapon of the wartalons.