@Pletse, Are you aware that you can download a gpx (from email, internet or wherever) on your phone, and open it directly into MRA Mobile bij clicking on it? This way you will find the routes under your profile-icon and then "Offline available". Both track and Route are visible and selectable for navigation there (if both are in the GPX of course).
@Corjan-Meijerink, maybe it is an idea to move that menu-option to a tab in the Routes menu. Or perhaps even to have it sync with the routelab. Ideas for a later date I suppose