I'm not sure that annotations are often used in Easymorph. It remains interesting because they appear in the final html documentation.
What if annotations of table were added visually at the bottom of the tables ? I would appreciate that it is done in the Main menu but if you think it would take too much space, at least it would be interesting to have them in the diagram view. Also annotations of group should appear in the diagram view, at the bottom of groups as well.
At the end if you implement it, the diagram view will become interesting for end users because you will see how the groups are used and each table inside. Alteryx does that. That's perfect to have a big picture technically as well as functionnaly.