Not possible that I know of.
One possibility would be to export the source database as/to a spreadsheet which you can then open directly in FM. In that process you can choose whether to use the first row as field names or data. If you choose field names you will have the field names side by side with the comment line and can relatively easily transfer the long name to the comment and substitute you preferred field name in the one process. (see screenshots)
It's still manual cut and paste and a bit of a pain but at least its all done in the one window.