This project retrieve MusicBrainz's data from the name of the artists. Because of this, there are some cases where the data returned is not matching the right artist (if there is a more famous artist with the same name for example) or simply if the artist does not exist in MusicBrainz's database. The location are displayed with MapBox. If the city is unknow the artist will be displayed on the country name. If two artists have the same location, they will be displayed on the same pop-up.
MusicBrainz is limiting the request at 1 per second, so it can take some time to load a playlist and for that reason only the 100 first tracks of a playlists will be proccessed.
As mentioned on the page, you can simply drag and drop a playlist on the page !