We are not understanding one another.
It's not a matter of the set editor not accepting a certification. Rather, the view in set editor does not show the 30 cent variants, despite them being in the set list.
For example, here is the view of the set editor for Warlock (1972). Notice that a user can enter values for all listings, including the 30 cent variants.
Contrast that with the set editor view of Warlock #9-#15 Starlin Thanos. The 30 cent variants do not appear. There is no field for them where a user can enter a certification number.