A strange thing. It is impossible to make Kurviger drive this way:
Here’s what he does:
I have no idea what is keeping Kurviger from navigating this way! I have noticed that the OSM page navigation behaves similarly when selecting the GraphHopper engine – with OSRM that’s OK.
Maybe someone would kindly look at it. Please. Perhaps this is a map error, or maybe some oversight on the part of Kurviger (which I doubt).
For me it seems to be a problem of the map data to exit the roundabout at the correct position.
But I don’t know to make a change of data. Perhaps our OSM experts can change it.
My first impression was the same, but I think the roundabout exits are correct:
The issue might be on the entry to the motorway.
IMO there is an incomplete turn restriction (“only straight on” but missing the details.)
I would delete this incomplete relation, which is unnecessary anyway:
I agree, there is a bug in relation 8621615: The “to” way has no connection to the “via” node:
And - as @linux-user already mentioned - that restriction relation is not necessary, because the “to” way is a oneway.
So I removed that relation in OSM, that might help …
Thanks a lot! I would never have figured it out. I’m about to delete this relation and we’ll see what happens in two days…
Avoiding expressways with Kurviger, I would not have noticed this error if it were not for the need to use a gas station 
Edit: thanks @rumbrummer!
Your route link above now leads to a useful route - so probably the buggy turn restriction caused the deviation.
Sehr geehrte Herren,
in fact, it is already OK! Thank you very much for helping. It is very encouraging that Forum users are so helpful and selflessly kind.
Vielen Dank! 
