Hi William,
Thanks so much for reaching out!
Using WordPress’s export tool, you should be able to export your Additional Fields when you select Events to export.
Unfortunately, there is no way to export those Additional Fields as a separate file.
You can also add this idea to our Feature Requests, as we tend to implement ideas based on customer feedback, so your input is greatly appreciated:
https://tribe.uservoice.com/forums/195723-feature-ideas
Let me know if you have any other questions on this topic!
Thanks,
Jaime