Well, I can't download it, so I'll base my feedback on the screenshots.
I think the two block/elevations on each sides of both tori and uke are a bit redundant. Having just a flat floor and the slight elevation in the middle would make much more sense imo.
On top of that, you could add some more interactivity with what appears to be lava in the middle (?) (I was actually thinking of doing something similar with like a sword in the middle, and when you pull it out you could have a panel with thrust closing itself afterward.. king Arthur style for a proper flaming sword).
And you could either decorate the walls and remain very traditional in your spar map, or try something a bit original, make them high, and have some kind of vertical spar map with like grips and stuff..
I think all these little points could improve your mod, but apart from that I really like your colour panel (something I always struggle to get right myself), and the environmental aspect is very clean by itself.
Looking forward to see how this mod will evolve