As of now, Confluence new workbox notification feature will only be trigger by the following action:

The workbox displays a notification when someone does one of the following in Confluence:

• Shares a page or blog post with you.
• Mentions you in a page, blog post or comment.
• Comments on a page or blog post that you are watching.
• Likes a page or blog post that you are watching.
  The workbox does not show notifications triggered because you are watching a space. Only watches on pages and blog posts are relevant here.

The fact that update and edit on a watched page is not included as an event that trigger the notification feature is deeply disturbing since user watched a page to get notified. However they don't get any notification from the newly published workbox feature.

As notifications should include all notifications, or at least provide the option to do so, this feature is clearly missed out during development or during design.