How is your GRC system connected to the BI system in the landscape atm for GRC purposes? i.e. have you installed GRCPINW on the BI system and have it connected to the GRC system as a child target system? If the RFC's are working, then I see no issue with why the Basis team can not get the RFC's to work for the reporting extract.
Are there any plans form your basis team to make the BI system exist on the same type of server architecture?
Also, have you had a look at the following SAP notes?
http://service.sap.com/sap/support/notes/1729453 - This one contains a attached PDF describing the datasources
http://service.sap.com/sap/support/notes/1751453
http://service.sap.com/sap/support/notes/1675481
http://service.sap.com/sap/support/notes/1671161
Update - the following may be useful for your basis team http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/80095c7a-c587-2f10-3fb2-e827f3c45d35?QuickLink=index&…