I think this kind of effect is not supported by their algorithm. See the limitations section on page 10:
> The second assumption above is worth further discussion. When a generalized ray is partially occluded by matter, or falls upon the boundary between different matter (i.e., objects with different materials), interference between the different interactions arises. For example, on partial occlusion, interference between the matter interaction (of the partially occluded energy) and free-space propagation (of the unoccluded energy) results in free-space diffraction: diffracted lobes that “bend” around the matter. We ignore these edge effects in this work, and leave these for future work.
> The second assumption above is worth further discussion. When a generalized ray is partially occluded by matter, or falls upon the boundary between different matter (i.e., objects with different materials), interference between the different interactions arises. For example, on partial occlusion, interference between the matter interaction (of the partially occluded energy) and free-space propagation (of the unoccluded energy) results in free-space diffraction: diffracted lobes that “bend” around the matter. We ignore these edge effects in this work, and leave these for future work.