With respect to the postal codes: on the contrary, T2G 0G4 is the correct one. These commercial retail units (CRUs) have their own addresses on 6th Avenue (211, 215, 219, 233, 245) not shared with the Rocky Mountain Court apartment building (221). Their postal code is indeed T2G 0G4, whereas the apartments' postal code is T2G 0Z9. Likewise the pizza joint and Latino restaurant/bakery facing Macleod Trail have their own addresses with an entirely different postal code (T2G 2M1).

In effect you've done what you accused others of doing: copying from Google Maps. You saw an error there (the building's postal code), erroneously assumed that the building's postal code was also used by the CRUs facing 6th Avenue, and introduced an error on OSM based on that false assumption.

I've manually restored the correct postal codes. (See https://www.openstreetmap.org/changeset/169729713) Please be careful with postal codes downtown: many buildings have more than one.