Hi, I would like to point out that in Italy the street number identifies the access point (entrance) and NOT the entire building. In fact, a building can have multiple entrances and consequently multiple street numbers. 
So you have 2 options: 
1. If you know exactly the position (entrance) of the street number you are mapping, put all the address tags on a node on the perimeter of the building (also adding the entrance tag on the same node); 
2. If you do not have this precise information, you must put all the address tags on an adjacent node but DETACHED from the polygon of the building. 
Finally putting only the tag "addr:housenumber" is strongly incomplete you must also put "addr:street" otherwise it is a useless data.
I have already made the necessary corrections. 
Thanks and Happy Mapping!
