Hi CSG!
Topps had their printing issues with 1990 baseball, the "partial blackless" sheets as you know. They also packed out some partial yellowless cards from their D* production sheets which I believe is unknown by the card community. There are over a dozen error cards that were in one area on a few/several? sheets.
I've done a good bit of searching on online forums, sales sites, Youtube and have found no mention of the yellow errors. I viewed hundreds of images of 1990 Topps Sanders, Smoltz and a couple less popular players, found none. I did see a partial yellowless Danny Heep card a few years ago online but they didn't mention the error.
Would CSG authenticate, grade without knocking the grades for the partial yellowless ink (like grading companies have done with the missing black ink cards) and label them as partial yellowless error cards?
CSG could be the first to grade them, show the "yellowless" to the card community and I could get the first ones graded