Try using the 12-50 at no smaller than about f11 and preferably closer to f8. Similarly, the 7-14 does best right around f8. I haven't really evaluated this with my lens, but have heard the 12-50 is best 1-2 stops down from max aperture. At f22 you are well past the point where diffraction degrades the images you get. That isn't unique to that lens.
I have not used a diopter on the 12-50 and am unfamiliar with the one you are using; could that be at least some of the problem?
I have not experienced the focus problems or excessive softness you are describing with the 12-50, so I'm not sure what to say. It isn't widely regarded as a tack-sharp lens, but I am generally happy with it. The 60 is a better macro lens but of course you give up that zoom flexibility. Which is best depends on your priorities.
FWIW, my 60 does not seem to exhibit any softness or focus issues. Perhaps post some images?