I don't see any city information for any country. That might be a bug in Formidable's addon's data. I suggest logging a support request. I haven't used it in forever, but I thought it used to have it. That being said, of course you can add data. Just make a CSV that matches the format of the form (easily done by exporting the current Locations form data and culling out all the data except for the headers), add in a new line for all the cities you have and import the file back into the Locations form.