And also, is GPSApp useable for European Empeggers and where could I get (or buy) the maps I need then?

If you can find a web site that puts up European route information as latitude/longitude numbers (the way MapsOnUs does), then you could modify GPSapp's python script to screen-scrape that web site instead of MapsOnUs.

The reason GPSApp uses MapsOnUs is because it's the only web-based mapper that gives its routes lat/long data. At the moment, If it weren't for that site, GPSapp wouldn't work.