I actually think her not being as deadpan as in the OG twitter manga would make it not as good. Her "p-p-p-poker face" reactions made for brilliant comedy.
I really love the idea. I kind of hope her friend or she meets someone that can also see them but at the same time, I think that'd kind of take away from it. Also, YURI!
Is there a need to change prayer beads into rosary? Are you working for nintendo or something? It might seem harmless but it locks the MC's religion or beliefs into Christianity. Well, it isn't that much a problem probably, just me being purist.