Ok, so I tried this, and it was a pretty good concept, but the way you actually demonstrated it was pretty bad.
All you did was make a small map that used the 3D-2D effect, you could have made the 2D part much longer, and the 3D parts much wider, because they were way too cramped for a good demo.
The position of where you start should not be in the 2D plane, since you are not in 2D mode upon starting, I suggest a separate path that leads into either base for spectators.
It wouldn't hurt to have layers of rings or platforms at different heights in 2D.
Chasecam needs to be on by default in this kind of level, I'll add support for this for SRB2CB in the next version, you could also soc it to run a script at the start of the level.
Also, you certainly needed to use SRB2CB's custom camera effects, for CTF to work in 2D, you NEED to have the camera show what's going on as much as possible, zooming the camera out and/or making it rotate would have made it much more acceptable for seeing who's in front of or behind you.
And lastly, you set up the sides of your sky wall/thok barrier wrong, make the floor height and ceiling the same value, the floor height and celing should be as high as you want just the floor to look, and always texture the thok barrier/sky wall sector.