I successfully created a spreadsheet with drop downs for the default choices. I'm able to make my selections, than save as a .csv file and do the rest of the import.
https://photos.app.goo.gl/5e3igHZgYwwffHep9
I can't figure out the Background date fields though.
In your tool, which fields are you mapped to, the dates or the annotation fields?
My screenshot doesn't show it mapped, but I have mapped it, with what I thought was the correct format for a date and it didn't show up in either.
https://photos.app.goo.gl/Jjdcgz5NSyRNsqPQ6