Just a couple of notes:
The big boost jump in Crimson Construction Zone is pretty hard to pull off, even when playing alone without any lag. I can see many players getting frustrated with this jump.
Most of the rings in Frozen Slush Zone are not floating. You may want to fix that.
Bizarre Barrel Zone took a little while to figure out. You might want to consider making the spin elevators stand out more, so the player understands that they have to do something there.
Generally speaking, I think it's a good practice to have some leeway on jumps and springs. Just because a red spring shoots you 1024 fracunits up doesn't mean that the platform it shoots you to should be 1024 higher. Try giving the player a little room for error. It will make those jumps and springs less frustrating to do, and overall it will just make them feel more polished.
Anyways, I don't see anything that should block this WAD from being released, so welcome to Releases!