Unfortunately Blueprint Enterprise does not report on the type of paper such as gloss, plain or the many other types out there.
As you have discovered, there is indeed a paper size attribute for each transaction recorded within the Blueprint database. The paper size attribute is reported to Blueprint through Print Scout (a.k.a Tracker) data, as well as through copy, fax & scan transactions reported via Omega & Pharos iMFP Terminals. A paper type attribute, as you have described, is not captured nor recorded through any means, and is therefore not present within the Blueprint database.
I hope this helps to clarify the paper attributes that are recorded and reportable through Blueprint.