Thank you!
Direct sunlight definitely needs more work... I discovered direct sunlight isn't working correctly with levels of detail (mipmaps). I would also like to ray march light from voxel faces instead of from voxel centers for more accuracy. Furthermore, direct sunlight doesn't take into account lighting angle of incidence between voxel face directions (normal) and sunlight direction.
Once I've addressed what can be improved with direct sunlight, I will work on cone traced global illumination. That will both propagate sunlight indirectly as well as handle per voxel emissive lighting (and propagation of emissive lighting).