We'd have someone based in Brazil, Argentina for sure, even if they were independents. Then if a player needs scouting directly by the club they would send one of the numerous European-based scouts from the club.
A quick search, someone like this guy:
https://it.linkedin.com/in/giani-lorenzo-81ba01111
International scout, there he is at La Bombonera with a Boca scarf on.
I remember years back it used to be Renzo Castagnini who did the kind of 'final scouting' for the club as he was the chief scout. I'm not 100% who the chief scout is now. Most recently it was Pablo Longoria, and before that it was Javier Ribalta.