Those 1.3 million places from ~130 other sources, the website says that they are "often" with an open license. Would that be compatible with OpenStreetMap? Because then we could make OSM be a more complete map of the planet. Are you aware of any project that can show which places (from those other open sources) are not yet tagged on OSM?
Edit: to clarify, I'm not proposing an import (which is usually a hassle), but just a comparison to explore how many places are in open data but currently not in OSM.
Edit: to clarify, I'm not proposing an import (which is usually a hassle), but just a comparison to explore how many places are in open data but currently not in OSM.