Hi ndm, thanks for your explanation. It seems to me that you're conflating the physical occurrence of a structure (represented by building=*) with the activity / current use of the building. I don't think that it's a question of differing styles; the original proposal for the building=* tag clarifies this precise situation: see §Sub-divided buildings? in https://wiki.openstreetmap.org/wiki/Talk:Buildings. Here the distinct offices / shops can be mapped separately as office=* areas without a building=* tag. After your changes, by amending the  original building=* way to just represent the name=Civitanivi part, it reads as if the other 3 parts were demolished and reconstructed with only this part retained. The alternative of using the Simple 3D Buildings method (not indoor tagging) would still retain a way for the entire building with the role=outline. 