Notifications Page for the Musescore website
Musescore should add a notifications page on their website. This can be used to inform a user of comments or favorites on their score, or replies to forum posts. If the app were to get updated, it could give notifications to users as well.
Comments
It already has one, kind of :) Click on the Activity tab on the right above on the page to see all recent posts or hover your mouse over it, then click on My posts in the drop-down menu to see all topics in which you posted. I find that quite satisfying any need for notifications. But maybe you mean something different?