Solution : https://service.sap.com/sap/support/notes/781140 (SAP Service marketplace login required)
Key words : 
system generates error td604, operation short text, long text exits, attached correction instructions, bapi bapi_alm_order_maintain, solution implement, program corrections, language &, prerequisites
Related Notes : 
       
| 897391 | BAPI: Item text not adjusted in operation PReq II | 
| 860249 | Component long text is not updated in PReq | 
| 780775 | BAPI: Problems in text processing | 
| 708508 | Downgrade BAPI_ALM_ORDER_MAINTAIN -> errors |