Both lenses suffer from chromatic aberration, in different ways. The Zeiss picks up some red/purple fringing at f2.8 and f4, with either adaptor tested. Here the Canon (topmost image) is clean . . .
It’s fairly prominent here at f2.8 in the Zeiss image. The Canon shot is on the left . . .
The Zeiss’ lateral CA persists all over the frame, not just in the corners. The purple fringing is still evident at f4. The Canon by contrast has slightly stronger CA when stopped down. The following samples at at f11. Again the Canon samples are on the left.
I don’t think we can declare a winner in this category: both lenses are affected to some extent: the Canon suffers a little more at small apertures, the Zeiss in the f2.8–f4 range.