I am a bit conversant in some other languages - they only thing I found relating to a zapallito is a type of summer squash, often found in S. America, it seems to be round, green with a white flesh. But zapallito seems to also be a word used to refer to courgette varieties in Italy. Not sure you will be getting a pumpkin as per se with your seeds ???
Maybe plant some other types as well, just to be on the safe side :D