Hello,
@NiFirr Yes spectral shading/rendering is something we would like to look at but later as highlighted by @jblackwell .
@That_guy_over_there Refraction is done the same way with/without Substrate so the same limitation applies as compared to before.
@berguina I thought we were done with that but the engine is always evolving with Substrate catching up so I guess we will need to look at that again.
@DMDevil This is still in the backlog.
@apfelbaum The bottom normal is of lower quality since it needs to be aggressively packed. This is the same when Substrate is disabled. This is something we would like to improve down the line but we are fine with parity on that side for now.