I met the Black Rose somewhere in Africa (maybe between Wadi Halfi and Khartoum). I accepted the quest to meet up with her again somewhere. She indicated that I would know how to find her. The quest description in this Wiki says that you will learn that she is in Buenos Aires by "reading a newspaper in the Americas." I didn't make it to North America on this trip, but I kept reading the paper in Panama and South America, and never received her signal. (Also, the route I took in South America didn't lead to Buenos Aires.) I never heard from her again.
Where do you read that she is in Buenos Aires?