the problem is that I returned to the JEM 2.2.3 version, in order to keep my website functional. So I cannot experiment anymore. Is it possible to install two versions of JEM on the same site together?
I have now tested JEM 2.3.0 on another website. The tablestyle looks better than the responsive style, so at first I see no advantages of JEM 2.3.0. I will stick to JEM 2.2.3 for now. Maybe some bugs will be found in future.