Hi, 
I see that you requested a review. To answer your question: Roundabouts don't usually have names (unless they are big enough and have their own addresses) so it is correct not to use the name tag here. See https://wiki.openstreetmap.org/wiki/Tag:junction%3Droundabout. You can even use noname = yes to signify that it really does not have a name. See https://wiki.openstreetmap.org/wiki/Tag:noname%3Dyes for that. 
So I would in that case also remove the name = Knalhuttenweg tag from the western semi circle of the bike path. 
Other than that, your change set was really good! Thank you and happy mapping!