The fog in the rope-walking violinist shot is probably contributing to the unsharp appearance. The low contrast maeks the picture seems subjectively less sharp. I think I would try with contrasty lighting, and a sharp film, like Velvia--and with the camera on a tripod to rule out camera shake.
If the pictures still don't look sharp, I would then send the lens to one of the experts. Does the camera produce sharp pictures with other lenses? Could the camera's rangefinder be off?
The Summilux is not Leica's sharpest lens, but when stopped down 2 or 3 stops it is a very fine performer.