If anyone is curious, I found a hacky way to get around this. It seems like IFTTT can handle recurring events properly, so I use that to fire a POST webhook to FlowXO with the following JSON body:
{"event_name":"{{Title}}", "event_description":"{{Description}}", "event_location":"{{Where}}", "event_starts":"{{Starts}}", "event_ends":"{{Ends}}", "event_url":"{{EventUrl}}"}
Then you can use those attributes containing Google Calendar even details in FlowXO like normal.
This method has it’s issues- it’ll take some time to fire depending on when IFTTT catches the event, and error handling is practically non-existent.
At least my recurring notifications can get sent now!