@ Stephen Ray #133:
The lens was a Zuiko 3.5/135. Concerning the CA: Did you turn on RT's amazing automatic CA correction (Raw tab)? The 2 screen shots show an area at utmost left at 400%, with and without CA correction.
Hening,
I have now tried RT auto CA correction. It helps but still not nearly satisfactory. Sorry, but a rather poor lens.
One might zoom into the attachment to better discern the color problems. (Grabbed from the center white flowers that should be more neutral without cyan artifacts as well as other colors.)