I am sorry we had an internal discussion about this report a while back.
Let me update you on this:
First
Shift-enter is to continue writing at the current level in the hierarchy. Using shift enter to nest is wrong. You need to use enter-tab
Second,
We currently only support 1 tab or 4 spaces for indentation.
The actual Commonmark spec that determines when something is indented is quite complex, 1 tab/4 spaces is a crude approximation. For that you can continue here: