Hi,
if you need to cancel an event, it should be clear to match the entire event. You need to set a unique key to get the open event id. This will be handled by the matching groups. When I look at your text to match, I see that there is a matching group on time and date. This will not work, this is not a unique value for this kind of event. So, all dynamic values will not be good to bild a unique key.
Cheers,
Christian