Solution : https://service.sap.com/sap/support/notes/178430 (SAP Service marketplace login required)
Key words : 
install apar iy15028, -latin-1 iso8859 languages, iso8859 languages, apar iy11380, symptom translation, terms toupper, case mapping, hebrew reason, broke lowercase, aix release 4
Related Notes : 
       
| 432115 | AIX 4.3.2 and non-latin-1 ISO8859 languages | 
| 158774 | Incorrect case mappings in some locales | 
| 39718 | setlocale on AIX and table TCP0C |