Tilelayers on the serverside
 

I just noticed this now:
tiletype(), onwall(), onwall2(), etc. only look at tilelayer 0, not any of the above layers. Because of this, my npcs can don't see any of the walls in my level but they still block me (because my movement is clientside and theirs is serverside).

Ya, I've noticed this too and I thought I mentioned it to you.
Hmmm, I dunno about serverside, but have you tried level.tilelayers[1].onwall()/tiletype()?

Function not found. :(
That would be annoying anyways because I would have to loop through every tilelayer x_x