Hi Ralf,
Unfortunately the suggested work process (use of Private files, then copying independent duplicates into some shared Folder resource - hey, instructors need to figure out the need to create and hide it first ), can work only in some scenarios.
As an example, all of our courses have more then one person with instructor access, either it is support, or instructional designer.
Not having just one clear course-level repository right in Moodle is simply not working
We will continue to use Legacy Course Files area, but I think I have just found bugs with course backup/restore. Moodle just wipes the files out of LCFs during the process in majority of cases.