Solution : https://service.sap.com/sap/support/notes/1594293 (SAP Service marketplace login required)
Key words :
role import screen select 'skip' option, role import screen display, error 'child role <role>, import composite role, prerequisites brm expects, 'role authorization source', import composite roles, 'skip' option, composite role, role details
Related Notes :
| 1570971 | Composite roles cannot be imported without single roles |