The Living Spirit was a spell given to us by @SpiritSeer to help us get to various locations during the secret society. You can see the original post here
@Sellalellen This is true. I’ll admit, I was mostly just getting amused at the idea of being all ghosty and spooping Marty. 
Like a floating pencil or something, writing a message. 
But you’re right, there’s no guarantee the spell would be enough to pierce the veil. Even if we wrote a message on paper, would they see it? If the Low kids were blocked from seeing forum screenshots, the same thing might happen.