Say that three times fast.
I don't have the Kolari modded camera any more, nor the Voigtlander 21mm f/4, but while looking for another image I came across these crops I put together comparing the effects of the Kolari mod. Thought they might be of interest for some.
I focused on a central spot at f/4 here. These crops are from the left edge. The Kolari A7 camera is on the left, the A72 is on the right. You can see at all apertures the Kolari mod helps a lot, at f/4 its usable and at 5.6 the CV 21/4 is pretty good across the frame.
While shooting with the CV 21/4 I'd noticed some apparent effects of field curvature. I re-shot this same scene and "split the difference" so to speak. I do think that the 21/4 fares better on a stock sensor if you take this into account. It's still slight though and there are still advantages to the Kolari Mod.