Terminology is always subject to interpretation, people are trying to communicate complex material in few words or sentences.
'you are also likely willing to go to the work of making it sharp, but there is no necessary relationship.'
Very true, as Jim Kasson found when testing the LoCA (a key test of APO) and sharpness characteristics of the 65/2 against the very APO (low LoCA) Coast Optics 60/4. It handily waxed this fine lens, and drawing on Fred's review and user experiences, the 50/2 is in the same ballpark for performance (lpmm).
So it is the combination of very high focal plane performance with APO character that makes this 50/2 so enticing, even before considering its aesthetic value and DOF effects.
