i have already requested this feature, the competitor do this from years now, they have pre-events and after-events (hooks) and they look to response to complete the action or return the returned errors.
i think this behavior a great way to extend the software and give the developers the ability to do more features and staff . the events now in Blesta is just like a notification system about completed actions, and also i think is no sense for look for after-events return as the action is already completed.