well, as you can see, the original Sowerby drawing for Rd. 338298 is captioned 'double hanging basket' - so Thompson was correct in using that description (which presumably like me the lady acquired from Kew) - and it is denoted as CLASS 3, so certainly not one of the hidden CLASS 4 miscreants. Some researchers, as we know, used factory records only as their source, and others also included information from Kew.
Since this drawing is freely available at Kew, and was obviously seen by Thompson, then the conclusion might be that it has been omitted from recent publications by those researchers who used only the factory records - who knows?? maybe records for this particular item were lost or mislaid at the factory.
The same deductive reasoning may well be applied to the sugar. However, I've not checked to see if your comments are true, and it's too late at night to start now - but we trust you

quote............"so far I can’t find pieces in the catalogues that match either of the design representations."
Assume you mean the CD catalogues only, and not the books?? You probably won't find the sugar in the books - too boring, but since the hanging basket looks unusual, suppose there's a chance it might be in one of them.
However, as we know only a small percentage of the total images of the pressed Registrations appear in the books - I don't know how comprehensive the CD's are - you're the expert on these things Fred

I wonder if Glen Thistlewood might be able to assist with this matter - having seen the original factory records.??