Yeah for sure that boulder hint seems to be too vague...17 is actually the sum of 1 + 4 + 5 + 7, so you have to move those boulders only, in order to make it work. How did you come across that pass through error? I'm having trouble re creating it.
Yeah, I would not have guessed that XD Maybe add an extra hint to the book?
It's the area with the dead tree 'maze' when you first leave. I think there's a crack on the wall, I could walk straight up those two tiles.