How do you know the marker is misplaced? Maybe the roads are misplaced. Have a look at http://sautter.com/map/?zoom=17&lat=48.81125&lon=9.16585&layers=B00000TFFFFF
It shows a bit of a difference in the positions of roads between OSM and Google Maps. Which one is more accurate? I’m not sure. I don’t know if there’s any good aerial photos available for that area.
I notice that the roads on Google Maps don’t match up with the Google Satellite photos.