The moment they beat Australia I tried to find more about the foreign recruits. Unfortunately, even the Internet doesn't help much further. My bet, of course, is that Renan Ribeiro and Joao Neto must be Brazilians, but I guess they are quite unpopular even in their home country. Also, there must be typos in some names. Renan's family name is Ribeiro, John's is Chigbo, he is a MB. I can tell you more about the Serbian Milos Stefanovic; he used to play at my hometown club Neftochimik Burgas (Bulgaria) for a year, the 2010-2011 season. He is a very decent setter, the type that wouldn't have much trouble finding a club in Qatar either. I didn't know he had obtained a Qatari citizenship until last year. Still, he is part of a team that beat Australia and is currently leading 2-1 against Japan, so I guess he has been showing volleyball of no lesser quality there as well.
I checked my video collection and FIVB stats sheets. Renan Ribeiro participated at two Club WCHs with Al-Arabi Doha. In 2011 he was a libero, despite his 195 cm, and in 2012 he was an OH, his usual role. In 2012 he had a quite decent match against Zenit Kazan.