Thanks, @kfrajer, most grateful! 
I didn’t know about the first hint, thanks for sharing it, as well as the links.
I mostly care about the PShapes; the spheres were used for illustration purposes. But I was interested to see if the spheres were affected by the surface’s colors.
Here’s a gif of the original with the new hint:
Here’s a gif where I make both surfaces red (though they don’t seem like the same color due to the simultaneous contrast of their frames:
Seems the spheres use a different shading strategy…
Thank you again! Life can now continue…
Adding a couple more pertinent links Kf’s links led to:
- Program to test hint() with transparency (excellent forum post)
- hint() (processing ref doc)