Thanks for getting back to me.
I’m using google calendar, which doesn’t have an export option as far as I can tell.
However, your comment gave me the idea to find something that could export from it, and I found iCal Import/Export CalDAV. Using that, I exported all of the calendars to file, then connected to my davical server and imported all the previously saved files. That appears to have successfully merged in the events which were in limbo.