Hello,
The current version of phpdocx can't add comments from HTML tags, you need to use the addComment method. The next release of phpdocx will include support (there's no release date yet).
phpdocx 9 added support to add comments and many other contents and styles from HTML tags using HTML Extended available in Premium licenses: https://www.phpdocx.com/documentation/introduction/html-extended-to-word-PHP
Regards.