I just got a Cambo set with a SK 35mm XL and 47XL, I went out yesterday to try it out and found the 35 XL to be somewhat soft on the left side.
Today I went out to shoot a brick wall and yes indeed the upper left side is noticeable soft compared to the upper right side.
Here are some 100% crops, straight out of camera. Shot at f11 ISO25 on tripod. No shift / rise at all.
Is this what I can expect? It seems to me that it should do way better.
Left and right: