Currently you can't place carpets on framed slabs or place framed floor boards on normal slabs.

From what I can see framed slabs are already tagged as #minecraft:slabs. So not sure what the issue is?

the issue is they are both fancy block mimic tile entities that mimic the texture of the blcok they contain. Doing this would be a double mimic block tile entity, very confusing and require quite some custom integration code