there will never be general agreement basically of anything. that has a name, its called communism.
you cannot even decide what format should a text note have, or a video event. there are already multiple, and there will never be less, there will only be more specifications for the same thing.
kinds will collide and that is not a good thing. that means your client will download 90 % of useless events it does not understand because they do not follow the same format even though they use the same kind.