Thanks for the reply.
"To do this you would probably want to create a separate block..."
This would sounds attractive to some teachers, especially if we don't have to do all this manually:
"export the group grades as text and post them as a resource in the course"
The "block" mentioned in your post should do all this automatically and "at real time".
If the block only displays the "TOP 10" and if the course is MAINLY for students who are ONLY needed to complete tasks within a period, like reading one passage every day (as a reading habit training course), the "marks" shown will only be "done/not done" or "the number of passages read" or "the total number of words accumulated", and if the students understand the "TOP 10 chart" BEFORE joining the course, I think it will not be too serious a matter it seems to be when we are talking about "privacy laws". But...., I'm not sure.
Anyway, the block may just be a "tool" standing by for teachers to decide to use or not, I hope.
Cheers