Ok, thank you for that consise rundown. That was all clear to me from what Zuzana added to my observations.
The bugs that I described still stand though. Suggestions in a cleared CP (as in all suggestions that I did not confirm are remocved) will sometimes be added automatically when a control point is adjusted in 2D.
The other errors did also occur, although I did not observe them again yet so that I can make a screenshot…