Flexi Custom Code - Awesome PHP Code Insertion Module

Today I will introduce a free module for adding PHP, HTML, CSS or JS code.
Unfortunately the developer of this module has stopped working, but it still works on Joomla 4 - Simply because this module is not complicated.
I have used many Custom modules, but this is the only one that supports PHP language. Make you comfortable to customize the website (Of course if you know PHP - LOL).
This module is now out of JED, fortunately I have a backup. You can download it below:
Flexi Custom Code - Joomla 3 & 4 Flexi Custom Code - Joomla 2.5
I will have a series of articles related to PHP and will use this module.
InPre-Update Check for Joomla 5.4.4
for Off-Canvas it says
Joomla cannot detect the extension's compatibility with the target version of Joomla.
have you implemented the compatibility stuff for Joomla to upgrade extensions correctly ?
Have got two off canvas menus working (1. for tools and 2. for main menu)
However I can only get the Main menu to display the first level of menu items.
Have you any suggestions for getting the sub menu items to display ?
N.B. the menu item with sub menu items does display a down arrow, but trying to click on it only display the item at the main menu level.
see
https://siteupdate.vedicmaths.org/index.php
If you want to see where I have currently got to
What is wrong?
That imported page keeps on saying this, but nothing further is happening...
1. The "radio buttons" extra field doesn't transfer the values in the additional field, e.g., "yes" or "no," and only enters certain values into the #__fields_values database.
2. The "textarea" extra field with the "Use editor" option checked converts to "textarea" when it should be "editor."
3. In K2, the extra field group is assigned in the category. In Joomla Articles, the category is assigned in the extra field. It would be nice if this were automatically completed. A checkbox could be added if someone doesn't want this option.