A lot of work has recently (January 2024) been done on get_help_text() which has improved classdef documentation.  Nevertheless, the issues in the original submission remain.  In terms of priority, getting dot notation working for old-style classes would be useful so that programmers wouldn't have to switch syntaxes whenever they write object oriented code in one or the other styles.  Next most important would be supporting slash notation as an alternative to dot notation.

Another incorrect behavior is that if the method name is the same as a regular function then the class is ignored and help from the regular function is returned.  For example, inputParser has a delete method.  Executing

help inputParser.delete
'inputParser.delete' is a function from the file /home/rik/wip/Projects_Mine/octave-dev/scripts/miscellaneous/delete.m

 -- delete (FILE)
 -- delete (FILE1, FILE2, ...)
 -- delete (HANDLE)
     Delete the named file or graphics handle.

     FILE may contain globbing patterns such as '*'.  Multiple files to
     be deleted may be specified in the same function call.

     HANDLE may be a scalar or vector of graphic handles to delete.

     Programming Note: Deleting graphics objects is the proper way to
     remove features from a plot without clearing the entire figure.

     See also: clf, cla, unlink, rmdir.

which shows that the help text is coming from the wrong file.