The plugin is a good replacement for the former article comments function. However, in its current implementation, it does not provide feedback to journal admins or the authors of an article whether a public annotation had been added, e.g. by e-mail or another type of notification.
Hypothesis offers Atom/RSS feeds or an API (https://h.readthedocs.io/en/latest/api-reference/v1/) that can be used to track an URL - would it require a lot of effort to put it to good use?