Hi Mark,
The Facebook Events plugin only does a one-time import. It is not possible to sync the events so you can automatically get changes from Facebook. If you do make a change to the event on Facebook, you could delete the event on WordPress and then re-import it from Facebook. I know that’s not optimal, but it is at least a workaround.
We would like to be able to synchronize events from Facebook, but there may be limitations based on the Facebook API. If you’d like to encourage us to look into adding that feature, you can vote for it on the UserVoice page.
Best,
Leah