Closing note as unverifiable.

OSI MapGenie Standard (for reference only!) has the two neighbouring buildings as nr. 10. Search results in
"10 COLLIER'S LANE, HIGH STREET, KILKENNY, R95 XHR0"
https://webapps.geohive.ie/mapviewer/index.html

The Mews is not a housename I can find documentation for at this location, so it may as well be a description. (would be 'a building that was used in the past for keeping horses and is now used as a house' according to Cambridge dictionary); such a building may have stood there or nearby.

Fyi if they can verify it has an unsigned housenumber or housename, you may use this tagging or similar

addr:housenumber=*
addr:housename=*
addr:housenumber:signed=no
source=local knowledge of owner of The Involvement Centre

though we usually only map signed details for verifiability.