You do have your Headings 1-9 properly set up.
Your custom heading styles are not. Again: How to create numbered headings or outline numbering in Ribbon Versions of Word by Shauna Kelly
That article shows the only way to use automatic list numbering on documents that are likely to be edited, especially by different people.

See also Why use Microsoft Word’s built-in heading styles? by Shauna Kelly.

For other options that do not use list numbering, take a look at Numbering in Microsoft Word. Especially look at the SEQuence Field.


Off-topic: For constructing legal templates, see also Automated Boilerplate Using Microsoft Word.