Ernst, your mention of Qimage reminded me that, a few years ago, Mike Chaney made a serious effort to convert Qimage to Mac.
While I don't remember, or know, the exact reasons for his giving up., I believe it was. The very difficult technical issues with interfacing with the Mac OS and the lack of support and information from Apple.
Trying not to be an Adobe apologist, I would guess the reason for these printing problems may not totally with them.
Of course, proper testing, by definition, would have caught it. However, it is easy to get caught in the error of, "We didn't change anything in that code, so of course it will work.". That's why I had others manage the test bucket....not a marketing, quasi-engineer such as I. 😀
John (from jrsforums....don't know how that email address got captured....?? I did, yesterday, restore my iPad....see, ya gotta check EVERYTHING