by Ken Task.
Mark is indeed correct, if you have a site with many courses to move to 2.3. You could install the desktop version of 2.3 and get your courses restored locally. Then backup as a 2.3 to restore to your server.
Question: were the courses in Hebrew? Were the files contained in courses you are trying to restore named using Hebrew?
Take it the 2.3 server has appropriate language supports installed.
And there are no errors in apache error log that might give a clue?
How about in moodledata/temp/backup/ ? Any files/folders remaining in there after an attempted restore?
'spirit of sharing', Ken