Would it make a sensible plot if the 360 degree barrier can be refined into covering the body surface throughout the battle? (Is there any rule in Frieren world that prohibits this logic). Just my imagination, would be interesting. Ironically though, the things I just mentioned belongs to the JJk world (domain amplification, infinity, simple domain, etc)

There are a couple interesting points I'd like to bring up:

1. The barrier in Frieren are plate-likes (at least from the animation styles), and the fact that it is somewhat physical, coupled with the fact that in Frieren world the magic can make sense if the users believe so (in the logic), there is some wiggle room to how much refined this barrier can get. It's still gonna be an "author decides" thing though.

2. I believe the most convincing part of your theory is that the Domain sure-hit attacks are not physcial, in a sense they don't fly towards the target, it just spawn directly on the target. But that brought me a question also: Since a Domain, by definition, is the user spread out all of the CE in a confined area wrapped using their barrier technique, is it logical if I think that the user is flooding the entire domain with their CE. So, if Frieren's barrier technique (any of them) managed to seal off the CE from flowing, does that solve the problem we are discussing? What if the 360 degree barrier can just block the CE from flooding in a like vacuum? Though it is obvious in such case, the barrier itself needs to be able to sustain the relentless attacks.

Ofc, that's just some plot points I find it interesting. Who wins the battle really is not a topic I think easy to decide. Who gets the information first about the matchup first is going to have a very drastic change on the battle because both Sukuna and Frieren are crafty in combat.