hi Stephen,
Rolling back to previous versions of Moodle, whether in
MoodleCloud or hosted elsewhere, unfortunately isn't an easy thing if at all possible. The best way to go about this, is to look for an alternative design using the tools that are available to you.
I checked to see which plugins you have available in MoodleCloud, that may be of interest:
Checklist activity - this can be set up to display all
activities being tracked for completion, so your students can see where they are progress-wise
Course completion (settings and block) - as a student, you can open a report listing all the conditions and their statuses for completing the course
The human side of change management is a daunting task, I can tell from experience. People don't always appreciate change, especially when it comes as a total surprise, so I understand where your students are coming from. But... I expect the MoodleCloud / HQ team to have given you a heads up about the upcoming upgrade to Moodle 3.11 somewhat in advance, so admins have had the time to prepare for it.
The best thing to do, is probably this:
Take a moment to accept rolling back isn't an option, and then make a plan to answer the following question: How do I optimize the new tools and interfaces I have to help my students understand what they're doing in Moodle?
If your students are so focused on keeping track of their progress, then modify your course's design to provide them this information through the Checklist activity and/or the Course completion block.
If your students have lost their way around your course page, take the time to setup some User tours (if you have access to them under site admin > Appearance) to point out how the new version of Moodle works.
And if you have some time available, you could even go as far as adding some Label resources to your course, setup through Restrict access, to only become visible once a specific activity has been completed.
If you have the means ($$), you may want to reach out to a Moodle Partner close to where you are operating, for more hands-on support than these rather general recommendations.