Solution : https://service.sap.com/sap/support/notes/95681 (SAP Service marketplace login required)
Key words : 
smlt -> schedule import -> special imports -> export set, select -> special imports -> development classes -> export set, select mode 'change requests', find development classes starting, target system transaction smlt, customer system customer developments, dialog box displayed subsequently, sap standard transport programs, select 'customer-development', customer - ignore tresc
Related Notes : 
       
| 1375438 | Globalization Collection Note | 
| 491522 | REPT RPUREROL/ ES Version text element IP01 was too long | 
| 490323 | Incorrect Spanish standard translation travel expense form | 
| 429041 | Missing translations of error Message >3 535 (Cash Desk) | 
| 138184 | Missing translation (table contents) | 
| 100168 | language export 4.0B | 
| 18601 | Frequently asked questions on language transport |