In the <package/> node at the top of your xml add ignoreWarnings="true"; maybe something like `perl -pi -e 's/<package/<package ignoreWarnings="true"/' file` ahead of the import call.
Obligatory note of caution:
It looks like you're automating import of campaigns uploaded to an sftp. Just know that there is a ton of danger in this, ranging from innocuous user error to not-so-innocuous trivial root exploitation of the app. If you're sure of this approach, consider at least adding a check to constrain import to nms:operation schema.