I found an issue when planning a route where the result is not the obvious shortest path.
You can replicate it using 47°54'17.579"N, 7°5'24.582"E as start point and 47°54'19.828"N, 7°5'25.319"E as end point. These points are close by on the same trail but the resulting route goes a long way around to link them.
It might be an issue with the underlying map and not fixable from your side.
Thanks for developing this wonderful app!