Have you converted the files before running the game? You need to go into "converter" folder in the "editor" folder and run the "ConvertCustomImages.exe". If you need step by step instructions click on "Use Custom Images" button in the editor. The data itself look fine so it might be that.
I forgot to, thank you. But some other weirdness is acting up now; if I assign the (now converted) assets, the game locks up during launch and crashes. I was able to move the assets to a clean copy of the mod tool and even got them to boot in game and work properly by applying them to one of your tutorial levels, so it can't be the assets themselves anymore...
I must have something fucky going on, so I'm going to bring over elements of my game crashing folder to the currently working one until I find what's causing it to break. If I find out I'll let you know. Cheers.