So, I guess despite the demon ghoul massive size, it was able to pass through those human-sized doors by shape-shifting (like it went from a centaur form at the end of chap28 to a slithering one in chap29). Still, we clearly see in
chapter 28, page 7 that the boss is
at least 6 levels under (the girl cast from X, and a doll open XVI). This was after the MC used his Auto Battle, and after a flashback from her parts. By the time the boss is arrived at the 10° level there is no way at least 1 minute is not passed. By the time the boss appeared, or when she started monologuing, instead of remaining to listen to her, had he a speck of intelligence he should have hit that return button.
Her party companion should have been in no danger by that point, the incantation on the door (which she opened exposing herself) should have probably been enough to block it, unless the church cheapened out by putting weaker charms the more up.