text: OSM doesn't actually contain postal codes for most residential buildings, because they are not open data (Canada Post wants to sell them to you) and difficult to determine otherwise at scale (knock on every door and ask the residents their postal code?)
  
  The postal code you might be seeing when doing an address lookup is the nearest known postal code, but with area of a code being very small, it might well be the wrong one.
  
  Your update of the address points https://www.openstreetmap.org/node/2431670181 might work in this case. But just letting you know why postal codes are generally a problem in Canada.