Estuve investigando, porque la verdad nunca he tenido la necesidad de utilizar PayPal pero mira lo que encontre:
Cita: The country code is going to override the lc variable. So if you have the lc variable set to "ES" and the country set to "US" the country is going to be US, and the language displayed is going to be the default language of English.
<input type="hidden" name="lc" value="ES">
<input type="hidden" name="country" value="US">