Solution : https://service.sap.com/sap/support/notes/39763 (SAP Service marketplace login required)
Key words : 
registry key hkey_local_machine\system\currentcontrolset\control\nls\language, hkey_local_machine -> system -> currentcontrolset ->      control -> nls -> codepageif, windows nt    xx   xx     1401 1401 croatian_croatia, 28592            windows nt    xx   xx     1401 1401 romanian_romania, 28592            windows nt    xx   xx     1401 1401 slovene_slovenia, -------------------------------- missing language/country combinations, windows nt operating system, slovene microsoft supports      croatian, windows nt system directory, german windows nt version
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