The mechanism that actually matters here is insurability, not the score itself: if an insurer will not offer standard coverage, or prices it much higher, because of overland water risk, that cost gets factored into a buyer's decision the same way a large repair bill would.
A property's real exposure depends on its specific elevation, drainage and history of water issues, information the City of Saskatoon holds for its own infrastructure planning, and a $400 to $600 home inspection is more likely to catch an actual sump pump or backup valve issue than any risk score is.
Joel Dyck can pull the relevant City of Saskatoon information on a specific property before a score becomes a negotiating point in a sale. Get your hand-reviewed valuation from Joel Dyck.