Nice work!!
I have been using my Autocollimator to do similar. I found there is some curvature of field at infinity.
The Siemens Star on my Autocollimator is not calibrated for resolution tests, but using the information on resolution you have measured, gives me a rough idea of what to expect.
I don't have an "A" to check but I have been looking at my LX and Yashica lenses with the Autocollimator. In case you don't know, the Autocollimator views a projected image of the star pattern right on the film plane. If the pattern is not perfectly clear, it is due to the test lens resolution being less than the star pattern.
These are actual images though the Autocollimator eyepiece. Not Minox, but an exaggerated example of center vs edge resolution changes that can be observed.