I'll ask the Development team if it's possible... . There are some effects and blocks the vox-l simulator can't render yet. Since LearnToMod works best with Minecraft, why not try testing your mod in Minecraft? (Let me know if you're having trouble connecting)
Eventually, we're planning to do away with the old interface (the unity simulator) and replace it with vox-l, just to warn you. I'm not sure when that's going to happen though. We recommend using the vox-l simulator as much as possible, so everyone can get used to it.
For advanced level badges (badges outside of the skills and drills section) we always recommend pressing the skip simulator button and testing the mods in minecraft.