If they were downloaded as .gpx, they would typically be in the Garmin\GPX directory or a sub-directory. This is common across all Garmin handhelds. Filename will vary. Not familiar with Wikiloc trails specifically, so cannot comment on names.
This assumes that they were loaded as tracks or routes. If they were courses, they would be .fit (not .gpx). And would presumably located in Garmin\Courses.
