Comments, not notifications. 
Sorry to be a pendant but we already know there’s no planned notifications for these types of changes, which is why I am proposing they be comments instead.
Each time, or only within a certain period (eg. With the same day)?
I think the revamp to combine notifications might address that:
Though I can still see combining them to make the thread on the observation a little neater, if multiple media edits are occurring within a short time period, rather than being combined.