What Rainer says, is that the purpose of the white shots in the Sinar eXposure is only
to correct lens color casts and fall off and therefore the white files can be softened a lot (by eXposure, not by the user).
This simply because the "shading" tool in eXposure does NOT need to be used for "Centerfold", "Dust", etc ... issues: that's done as well, in eXposure, and automatically, BUT NOT in the shading / vignetting correction tool.
The question being if other applications are doing this (centerfold & dust removal) during the shading or not: some certainly are, from my knowledge, and in this case the shadings cannot be softened by the software.
How to go about softening?