It's been a long time since I really looked into it but yes, I think it was related to the way Radiant 'pathed' the texture/shaders for the MD3 files, it meant that whilst they worked in-game when you opened them in the editor you'd just get the missing shader black/red checker. The odd thing, iirc, was that not all the models worked correctly when compiled so they must have included a number of broken assets in the editor pack anyway. I'm looking forward to seeing more from this project too.. Lordy knows it's been sat on for long enough! (real life etc.. etc..)