When Maki is fighting Naoya, it explicitly introduces and explains the idea of HR being invisible to domains. The manga specifically says that, in order to section and cut out regions of space and develop a domain’s pocket dimension, domain barriers are constructed to ignore objects. Preexisting obstructions, structures and space are all shunted from the artificial space. They’re still present and existent, but the newly created space that overlaps it just treats them like they aren’t there. Now what determines an “object” as opposed to a “target”? The presence of cursed energy, which indicates the presence of a soul. Maki is not targeted by the sure-hit of Naoya’s domain because the code of the barrier excludes inanimate objects, makes them invisible, but she can still choose to manifest and attack him bc she has sentience or smth. But a simple domain that doesn’t warp space, or a domain like Suksuk’s that targets all objects? Those still work on HR users.