Hi, welcome, and thanks for the nice words 
You are describing two separate problems, let’s tackle them both:
- Wrong map data
The reason when things like that happen, is that Kurviger uses OpenStreetMap data, which is edited by the community worldwide, and can therefore sometimes be wrong. It’s like wikipedia for Maps. If you’re in the mood you can make an account there and correct some stuff yourself. If you live in an area where - appearantly, as you say - there are lots of errors, then you would really help everybody here, we would be super grateful! Kurviger would automatically use your corrections after all the server magic in the background has happened after a couple of days
- The Kurviger algorithm
This is actually something that Kurviger is responsible for. So here we have a result of the programming of this service. We had the discussion of splitting up a route (sometimes ignore main roads, sometimes not. Sometimes go fastest, sometimes go most curvy…) multiple times in this forum already, for example here:
or here:
Maybe you can go over into those threads and get some tips or participate in the discussion.
But maybe the developers could also change the algorithm again, to be less “avoid-y” inside cities. It’s probably not an easy change, though, and it could be very destructive to other things