Solution : https://service.sap.com/sap/support/notes/761574 (SAP Service marketplace login required)
Key words : 
fi documents created, media billing documents, error message ff747, tax line items, tax amount, program error, accounting results, terms jhf2, saplfaci reason, solution implement
Related Notes : 
       
| 720874 | Error message FF747 during billing data transfer with JHF2 | 
| 549712 | BAPI_ACC_BILLING_POST:Tax line items summarized in FI documt |