Hello shemag8,
To clarify, you are trying to add a creative under a line item that has text localized to the language of the country the ad is passed in, correct?
If this is the case, we do not have this functionality. The best way to do this is to have separate creatives with each language, under separate line items with your geotargeting as you have mentioned.
Please clarify if this does not answer your question.
Thanks,
Edward