The goal is to cover mostly the new EFL API, but fixes on the doxygen tree are also usefull. The new API is documented in .eo files inside efl.git, but not all of them are useful. The priority should be given on the src/lib/efl and src/lib/eo directory. Then only the file starting by efl_ in src/lib/ecore, src/lib/edje, src/lib/elementary and src/lib/ecore_con . Some of this function are loosily documented and should clearly be improved. Some have a documentation that is also not in proper English and should get fixed.
If there is limitation on the documentation system or request for improvement that would give better result, @q66 is the developer of that infrastructure.