Hi Derek and happy Friday!
I am sorry to say that there is no direct way to adjust the order of custom fields in Filter Bar at the moment. It may very well be possible with some custom development, but I do not have a workaround that is supported by the plugin.
I do see that there is an open ticket for this in our feature request forum though:
https://tribe.uservoice.com/forums/195723-feature-ideas/suggestions/13251324-control-the-order-of-items-inside-a-drop-dow-box-i
Would you be willing to add your vote to it and perhaps add a few notes in there about your specific use case as well? That will defintely help us as we consider it and other requests for future releases.
Sorry for the bad news, but does this at least help answer your question about the possibility of changing the order of filters? Please let me know.
Thanks,
Geoff