Some interesting claims. I had the CV 21mm on my E-P1, but both the Olympus 17mm and Panasonic 20mm lenses are sharper. The CV 21mm is a nice lens, but it is not performing better than the other two.
As far as the question about the discrepancy of the angle of cropped 35mm wide-angle lenses and there focal length, that has a simple answer. A single focal length does not really describe a lens with a rectilinear projection--magnification increases as you move away from the optical axis and, since focal length and magnification are two sides of the same coin, focal length cannot describe the image across the image plane. So with very wide-angle lenses, manufacturers have a target angle of view. The target AoV is related to the extreme edges of the frame, but will most likely not be proportional as you crop in. So these lenses can have a greater angle of view on a m4/3 camera than simply halving the focal length would suggest. The CV 12mm is a case in point, it is closer to a 21mm lens than a 24mm which is why there are so many photographer recommending the CV 21mm viewfinder for it over a 24/25mm viewfinder.