Andelin, I don’t have any specific references for you but here is a place to start:
http://www.harpspectrum.org/folk/History_of_Latin_American_Harps.shtml
You/she might also try contacting some Latin American harp virtuosos specifically: two whom might be helpful are Alfredo Ortiz and John Lozier.
Geoff Welham has published a string chart for his Paraguayan harps that might possibly be helpful:
http://www.harpsatsang.com/harp_design/data/para36stringchart.html notice that the range includes Bb and Cs are blue, Fs red.
Hope this can get her started….
Biagio