I consider Luminosity winner to be NA team for sure. The only real ground for me in this dispute is where money comes from? (for salaries, marketing etc) and who are major share holders, and most importantly, what country an org is due to pay taxes. If all those conincide - then its easy to define. If not, for instance taxes are paid in US but main stock holders are from Saudi Arabia - then its partly US, partly Saudi org.
As an org founder i can hire 5 monkey to play CS (all those monkey could be from different part of the worlds) but if i am a US org my team of monkeys will be considered to be NA team.