For Melbourne, I will sometimes send the URL for the “Unknown - Melbourne” “artist” to other street art hunters/photographers who are not Melbourne SAC hunters - to ask them if they can help us identify any, this is a very useful thing for me.
Could the issue you had with Seattle or Seattle, WA be fixed by a further edit check on the artist name field that doesn’t allow any name that begins with “Unknown - “ that doesn’t match the concatenation of “Unknown - “ and the actual city name?
As a CM I have no issue with making it a little harder for a hunter to add an Unknown Artist marker as it seems that there is far too many adds of these on the platform that are easily identified with a little effort and there are some hunters who are not taking that effort.
If we are looking to measure Hunter performance with a leaderboard, I’d even say take points off every time a marker with unknown artist is added, encourage the effort to find the artist.
Also I’d love to be able to search for blank artist names for my city as a hunter, and for my country as a CM, so I could edit them correctly to the recommended “Unknown - Cityname” format.