So, I've quickly realized one problem: the bots are not good with the sewers. From entering the manhole in the previous chapter to leaving the sewers at the end of that one, their pathfinding is a bit off. Coach got stuck on the entrance to the sewer, they got lost or fell behind occasionally, and most irritating was the elevator part, where Coach refused to get on. Leaving the sewers, there's some glitches with the pipe, namely, that the opening is messed up and too small except for the left side. The bots do not like this area at all. After that, everything's fine again. Basically, you made a sewer level just like every sewer level ever made. I don't know if it's possible to make a good one anyways. I love the setting, and the school was groovy, but I would suggest perhaps more of the houses and school. More open houses to explore, more easter eggs, maybe the gnome, maybe some other stuff, and like I said, more school to explore. The last area was also a bit empty, but that's hard to get around, since parks are known for being rather wide and open. However, there is a way to solve this: crash a plane into it, and shrink it down. This easily fixes both the blandness and openness.
Not perfect, but not bad