It seems like all the building names like N220, N140, etc around here should be in the tag ref=* instead or in addition.
See:
https://wiki.openstreetmap.org/wiki/Key:ref
and
https://wiki.openstreetmap.org/wiki/Names#Name_is_the_name_only

Are these numbers like N200 etc also signed somewhere on or in the building or used as normal name for these buildings?
If yes and there is no other visible or more official name, they should also stay in the name=* tag.
If these things like N200 are not visible on the buildings or not used as names but only as reference numbers for the buildings, then the name=* tag should be removed and the info should be placed in the ref=* tag only.