As per my mail, the timezone, in the sense of the tzid for a zone, isn't necessarily going to be sufficient if the change involves the location of the event now being in a newly-created tzdb zone.  To handle that case automatically will involve an update to a set of machine-readable geographical-coordinates-to-tzid map and the geographical coordinates of the event.

(If the event ends up taking place at a location that straddles the tzdb zone boundary after the change, the correct answer might be to cancel the event and boycott that location in future events in order to punish the government for being blithering idiots; you *don't* put a time boundary right through a hotel if you're mentally competent. :-)  I'm not going to take seriously concerns about *that* edge case.)