KC just added passthroughEditErrors and suppressEditEventMessages to this section of the docs, and to the notes on DayBack’s updateEvent function.
Sometimes when you’re bulk-editing events, you’ll want the suppressEditEventMessages enabled to prevent the user from seeing a bunch of confirmation-toasts.
The passthroughEditErrors option is more linked to updateEvent. One example of where we recently used it is when we needed to make sure the event was updated before making some related join records. If Salesforce throws an error, you want to handle it in your callback so that your action doesn’t continue trying to create the join records.