There's another path that the author hasn't considered, which is making users contribute directly to OSM. To contribute a bookcase, ask them to create an OSM a

There's another path that the author hasn't considered, which is making users contribute directly to OSM. To contribute a bookcase, ask them to create an OSM account, log in with OAuth, and send the edit straight to OSM. Book corners becomes just a custom view and editor over OSM data, instead of being its own database. Users are now responsible for the data they submit (OSM already has tools to deal with vandalism etc...).