If you are using OSM then it would be for you to take the change request and then perform it yourself. Don't plan to do this at scale - just do it so that your client thinks they are getting full service. They wouldn't bother to do it very often.

But the real estate agents do get frustrated when its a real mapping error.

India - in Chennai they have 2 numbers on each house : old numbering and new numbering. So addresses are shown as 17 : 34

and the rickshaw drivers have never seen a map in their lives. I hold up a google map on the phone and they stare fascinated at it for minutes, but it really has nothing to do with the reality of getting there. Many people don't even know the names of the streets and they change the names all the time. Its done by corners and what landmarks are there.

curious - how did you come up with the name nestoria ?