Clip through a surface, not useful on this building cause it's not used in the run but could maybe be useful somewhere else.

I also found that some buildings have a hitbox on some of their walls, which can allow the player to stand on it, halfway to the top

That sounds useful !

You can use that, what Hi5 mentioned, to backup strat the long jump from one building to the other right before the cristal that spawns the brigdes to get to flag. Like as if you miss the ledge grab the character instead of falling to the ground just hangs on the wall collision and you can jump to the ledge and save the run