Solution : https://service.sap.com/sap/support/notes/140166 (SAP Service marketplace login required)
Key words : 
additional key words administrator workbench, source system, namespace qcm, table conversions, -alphanumeric character, 3rd position, reserved word, saa standard, solution bw 1, sap consultant
Related Notes : 
       
| 158843 | Logical name of clients in BW source systems | 
| 121163 | BDLS: Converting logical system names |