any way to make them revert back to normal?
I can't think of one.

Basically, I recompiled the w_grenade_heal model to w_stickybomb, so that TF2 uses it in game. However, when compiling and trying to get it to look for w_stickybomb materials it didn't work, so I just went straight ahead and let it look for the materials in the w_grenade_heal folder instead.
What's happening to you is the server is allowing custom models, but not custom materials. The best I could do would be to attempt a recompile of the model so that it's looking for textures in the w_stickybomb texture. That way it would use the default. So, it would look weird, but you could tell the difference between red and blue.