I like to adapt tracks (which I downloaded from any 3rd party GPS tour services) to my needs and send them to my Edge 820.
Unfortunately there is no direct way to create a course from a file (e.g. GPX, TCX, FIT, …) with GC.
The detour with uploading the file as an activity and creating a course from this activity works. But this is really annoying because I have to manually delete the activity (otherwise statistics are wrong) and also if other services are connected (e.g. STRAVA) I have to delete the activity there as well.
Please add such a direct course upload to the GC course editor. For me this would increase the usability of GC significantly.