I didn't receive any file, so I tried to make a test with 2 files and 2 words (just for test). I created:
ZaMsg_ar.properties.utf8
ZhMsg_ar.properties.utf8
I edit them, then I execute the commands (as a zimbra user)
native2ascii -encoding UTF-8 ZaMsg_ar.properties.utf8 ZaMsg_ar.properties
native2ascii -encoding UTF-8 ZhMsg_ar.properties.utf8 ZhMsg_ar.properties
zmcontrol stop
zmcontrol start
then I empty the browser cache
and change langage..and it works

see the attachment