That's not really how typing works, unfortunately. and I have to pick the type that we think works best. For the Themed Items, we keep them that so the entire set stays together rather than be spread throughout the various tabs. That's generally why a clothing set might all be clothing (when there's a food or two involved).

The antique shop and cash shop are different code! The Antique shop isn't sorted by item type twice, it's sorted by shop + type. It gets a little dodgey if we tried to do type + use in the cash shop because beanbags and stickers aren't technically marked for a use in those collections like books or plushies are. No matter what, it'd have to be something in the future if/when we revamp the cash shop shop. :)