I've tested in Usability Scenario #6 how beginner users are trying to insert a Chart macro. No user succeeded and they've abandoned the task after 10minutes.
The main issue is that we don't provide any default values for the macro parameters.
Ideally, users would select a macro and be able to press Insert with some good defaults for the macros. They would after edit the macro parameters to add their own. Currently, inserting a macro results in an error.
Without a link to the documentation (which we don't have either, see XWIKI-4448) there is no chance for users to use more advanced macros.
See related proposal https://design.xwiki.org/xwiki/bin/view/Proposal/MacroParameters