Solution : https://service.sap.com/sap/support/notes/1114633 (SAP Service marketplace login required)
Key words : 
unicode solution import sap gui, import sap gui, 'null' object reference, unicode characters, gui elements, symptom recording, ecatt script, chegui command, getgui command, japanese texts
Related Notes : 
       
| 509992 | Composite SAP Note: eCATT recorder | 
| 96885 | Downloading front end patches |