What's a nice response to my friend to something a bit kooky she wrote me?

I'd honor what she feels about it whether or not you agree with her conclusions. So in other words, I wouldn't share your thoughts because they will only make her feel bad and you can't prove or disprove things like that. So just go with it, especially since it evokes fond memories in her. You're a good friend to your friends, E and a very caring person.