the room isnt just made of nen. it exists "somewhere else", since both Cheetuh and Morel ceased existing in the real world. They vanished from there. So itīs not just nen, they really are in some other dimension. the walls being solid or not doesnt matter, imagine you were hovering inmidst space, nothingness surround you. What would you break? Even if you "broke" your surroundings, where would it lead you to? That is what I mean.

Youīre assuming that Cheetuh and Morel are still somewhere in the real world, so that when those walls are broken, the prison boundaries are kaput and they both return back to normality. Like they were shrunken before or something.

From what Ive seen, you cannot safely assume so. Rather, Cheetuh and Morel are in a whole other time space continuum now.The walls of his personal dimension cannot be broken because thereīs nothing beyond them. So either theyīre indestructable or infinite. I wont say that is a fact, since itīs very much possible that the author has it intended exactly like you assume. But it doesnīt make much sense to me.

The most interesting piece of information weīre missing is what is happning once 8 hours have passed, anyway.