capability management

[ak4t0sh]

Implementing function such as is_allowed_to_display_students() add complexity to your code.
It should be replace by

$hassiteconfig = has_capability('moodle/site:config', $context);
foreach ($mycourses as $course) {
    $coursecontext = context_course::instance($course->id);
    if ($hassiteconfig || has_capability('moodle/course:update', $coursecontext)) {
    ...
    }
}

which do the same thing but is more performance efficient (check for moodle/site:config is done only once) and more straightforward to understand for reviewers :)
It also remove the global $context usage which is against Moodle coding guidelines. Global should by use only for moodle core global variables.

Optional (non blocking for approval) :
I think that instead of using moodle/course:update you should implements your own capability. This way you could use this plugin on role which do not have the permission to edit the course (such as tutor for example)