Well i was never planning on releasing this addon, i am using it internal in my project, but i see your point in trying to hack that in the framework.
but now as a counterpoint for more extensible addon. there should be a clean way of publishing a message, and having a set of instance be able to subscribe to that message type, and trigger some type of functionality. without having to couple the instances to the messaging system. it would also improve event sheet maintenance if your are designing your event sheets in a modular way, you might not want to mix concerns.
a common example is pausing your game? that is a cross cutting concern across all your event sheets? you have to disable some button collision, reduce the time scale, hide/show new elements, these things might be implemented in different events and you might not want to mix that logic. can we just emit a message (in this case a string) "pause" / "unpause" and fire off a trigger to all the instances/system that are subscribed to those events?
i guess there are multiple ways to handle the situation, i am just trying to apply different concepts to implementation, which might not fit so well, writing this you could solve that issue by having a separate event sheet dedicated to your cross cutting concern, and that event sheet will be aware of all the instances
i was just dreaming of a more flexible approach, where i can just attach a behavior to the object and set the message to listen and have it all happen auto-magically so i would not have to duplicate those events.