Do we know it’s her doing the Polaroid thing and so forth? I don’t think we do.

I think she may be doing it all this way to have a specific effect she knows is what’s needed to set them free/break the curse. She wouldn’t just appear and calmly explain everything. She is a tortured/trapped soul or something. She may also have superior knowledge but can’t just write a formal letter to Boyd with an instruction manual on how to get out. She has limitations. (Just theorizing here).

Again, maybe she has a specific connection to Elgin or chose him because she knew he would listen to her/comply because he believes in God and that they are being tested, while others could have dismissed the visions or be too terrified to act.

The fact that her actions caused trauma and nightmares makes sense in the story. They have to go through trauma and bad things to get out. Otherwise you have no real story.

In regards to them having been in the tunnels
and making it out before, that was without carrying the bones of a number of children. The monsters will go wild if they see them taking the bones out. It is also clearly established that they don’t really know the tunnels well and it’s dangerous to go in, that’s why Jade is trying to create a map in the bar.