Currently, the system notification only says which doc and who sent it. The message content is not displayed. Tapping the notification brings you to the section from which the notification was sent. If there are several notifications, it’s not clear which notification you followed (assume the last one?).
Suggestion: Tapping the system notification should bring you to Coda’s list of in-app notifications. This will allow the user to see the notification content and select which notification they wish to “open”.