Having a relation as member of a route-Relation is quite uncommon, but I think there's nothing that forbids it. It might be better to add the ways directly (copy and paste should work in JOSM).

We don't have many running routes yet, so support is limited. You can always display an individual relation using the OSM Relation Analyzer or use Overpass Turbo for all routes in a given area, like so:
http://overpass-turbo.eu/s/1xuV

You also might want to file a feature request e.g. for waymarkedtrails at https://github.com/waymarkedtrails/waymarked-trails-site/issues