We have already discussed these issues with @dan.studio55-jp through another communication channel. For reference, this is a summary of the discussion.
Rather not. We focus on developing Shapespark as a tool for producing good-looking visualizations, where the final visual effect or production time are often more important than strict physical accuracy. Illuminance calculation, on the other hand, requires very strict physical accuracy, so a different approach.
It is a matter of scene complexity or GPU power. VR mode requires each frame to be rendered twice: once for the left eye, and once for the right eye, so powerful GPU has to be used to achieve frame rate high enough for lag-free experience. In particular, mobile-based VR devices (including Samsung Gear VR or Oculus Go) are not capable to render complex architectural scenes without lags.
In this case I would advise to either switch to desktop VR device (Oculus Rift, HTC Vive) or to reduce scene complexity by decreasing the number of triangles and lightmaps.
When an update is ready, you should see a small window shown below. The windows asks for confirmation before switching to the updated version. As long as you do not click the “OK” button, all the existing editor windows and baking jobs will work uninterrupted, so you will be able to finish your tasks and save all scene changes. Could you test this approach during the next update?