Solution : https://service.sap.com/sap/support/notes/1396403 (SAP Service marketplace login required)
Key words : 
h50    annexdatenh51    annexpacketi50    annexpositioneni51    annexpacketsave, original language   detarget language     enin, original language   entarget language     hein, goto -> text elements -> text symbols, function group named megui, create 4 text elements, h50    annexdatah51    ann, annexing tabs text, purchase order transaction, run transaction se80
Related Notes : 
       
| 980626 | SE63 Translation Transport | 
| 585116 | Translation after installation of WebAS SP25 |