actually that's interesting, you could make a plugin log which events it changed. I don't think there's a handler for listening to when events change, so you'd have to ask the plugin to tell you.
the problem is unless you want to store every single event in a gml, you'd have to find a way to retrieve the event from an object, and store it somewhere for later use, if you want to revert it. It doesn't really work like that, because you can easily turn a string into code by executing it, but you can't necessarily change code, much less compiled code back to a string.
There actually might be a way to retrieve events in string form or something of the like, but gml lacks so much documentation and user submitted questions about these kinds of things (mostly since most gmk users don't do anything really advanced with gml) that if there was a way we probably wouldn't know it.
All in all it's probably just not worth saving that small startup time.