Monsters can't be trapped / Talismans don't protect individual rooms

I'm rewatching From with my bf and I realized that monsters can't be trapped and we've known it from season 1. When the dumb dude let the blonde girl in, they closed the window once she entered and the talisman was still in place. After she killed him, she was able to open the window which means if they tried to trap a monster inside a house, it could open the doors and walk right out regardless of the talisman.

Another thing we've noticed is, the dumb dude met up with the blonde monster in a room and closed the door behind him. She was still able to get to the rest of the house, even though the rest of the house was a closed space protected by the talisman. What we're still trying to figure out is how was that possible, when Fatima and Ellis were protected in the same way at the end of the episode.