Simulink 2019b Menu Customization Backwards compatibility

SI have an old third party SW add-on that adds a menu to the old tools menu in simulink. This menu has been removed and remapped for the default items, but the custom items are no displayed anywhere. How can this be updated/solved for 2019b?

The add on works just as described in:

https://www.mathworks.com/help/simulink/ug/adding-items-to-model-editor-menus.html

But this process works no more for 2019b.