Tribes2RPG does have a lot of code completed, and the remake of keldrin is very nice indeed. The mod is very far from complete though. After scanning through the code it seems the exact point they left off was where they could not enable interchangeable skins on the player model. I'm guessing, but It looks like they tried and could not figure out how to do it due to the partial code left hanging on the skin switching methods. Its like the skeleton or uber in tribes1, where the skin is hardcoded onto the shape. The fix to this is to either make an all new player model (models) using correct skin methods, or if its just not possible - recompile a bunch of player models each with their own skin.
If anyone knows where to get the tribes2 3dsmax tools, or tutorials on correct skinning methods, (TGE tools may do it, have not tested though), it would be the first step on completing this mod.