Since the XML import kept failing I tried the export captions and CC option that Rod Ward mentioned in another post. It exported fine but when I open CP 2017 to import the caption and CC the option is grayed out.
You can only import such a file when it has been exported from the same project.
Correct. All of the Identifiers for the objects that hold the text much match perfectly otherwise the import will fail. So after you export captions from the project and send the exported Word doc off for translation you really need to leave the original CPTX alone and change nothing.