Solution : https://service.sap.com/sap/support/notes/436165 (SAP Service marketplace login required)
Key words : 
note 764480
Related Notes : 
       
| 764480 | SAP WinGUI I18N Trouble Shooting | 
| 382285 | Some characters are converted to '#' in SAP WinGUI | 
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| 176097 | Character of MS-windows change to ? after saving | 
| 110910 | Deleting the language load | 
| 104521 |