I dropped it halfway so I already know that she can't see but don't ya think if everybody else see's something except you, there obviously something wrong? I get that she only saw them as psychotic heretics but any sane person who experienced things wouldn't be sane anymore ಠ_ಠ there's no logic behind her actions except for adding survival tactics each time she dies when her scheme fails to escape regressing again and again, at that point any real person would forget their original state but she still thinks of going back to her old world even when she keeps regressing ತ_ತ
The key word is normalize. What you see and what she sees are different, so even if there's some poltergeist on scene, she can't see it and the world normalizes it for her. Someone getting attacked by an entity to her is just someone trying to off themselves.
She can't forget her original state and must stay focused on going back, all her attempts are to go back because the people of this world are the ones who kill her each time for ridiculous reasons like leaving the church. Even after she left, they still chase her down. If you wanted her to go crazy, that would be the worse outcome because she's be seen as a worse heretic and just be killed sooner after regressing. She has no power to protect herself against real people with swords and a burning stake readymade.
Who would want to stay in a world where the majority wants you dead? There was no other route for her but to be a puppet of the church and be constantly on guard because they never trusted her no matter how her status has changed, always looking for the slightest sign of heresy so they can burn her again.

Why is she lowkey dumb for someone who spend all of her time being an editor for rofan novel? Like even if it rofan, the fact that you are there are not a normal occurrence either, so you shouldn't judge anything based on your standards. Evil spirit and ghost might exist or the novel might not the same as what you remember. After all there's must be a reason why she was there in the first place. But she is so careless in her first and second regression. I had to bite my nails hard reading that