Closest event is 'Unit starts casting ability' it fires bit before actual ability effects take place.
Then there is under hero events 'player pushes UI button' which is meant to be used in single player.
I was wrong before, under game events are 'hero ability button is clicked' and 'build structure button is clicked' these are only events which I think exists.
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.