This is most likely because the mod is outdated, I pushed a couple of updates to regular Dicey Wastelands after taking over which caused a couple conflicts with my prior mods, I might eventually update my old DW addons, but I doubt that's gonna be the case.
If I had to guess, the reason why loading the addon externally to DW works, is because it might be overriding some of the original mod's behavior, which is what also causes the errors to appear.
For now, assuming your current setup has issues, I'd recommend you go back to the last update posted by MysticSword (instead of mine) on DW if you wanna use my addons.