I think it’s a real good idea The beauty of Fibery is that is super flexible and that you can create workarounds when needed.
When you use list view (or the new experimental new grid view!) you can change the order of items when you drag & drop.
For your situation:
- Link the lessons to the applicable course(s)
- Create a list/grid view per course.
- Level 1: course / Level 2: lessons.
- Create a separate view for course A and a view for course B.
- Use filter to only show the lessons that belong to course A or B.
- Order the lessons in each view via drag & drop
Only thing to be aware of is that you can’t use any other sorting (like date or name) when you manually want to sort them