I guess you could export a json with the Pretty print setting enabled (so that it's human-readable) and perform a search for the name of the event to see how many times it's keyed and in which animations. If you're using a text editor such as Sublime text you can also collapse rows.
That's the artist easy way to do it. More code-savvy people would parse the json and output this answer. 😃 (but I'm not among those as a humble artist)
