Can you use the problem font in word or any other program to determine if the problem is with the font or Manager for some reason not being able to access the font? it sounds to me like either a permissions or symlink issue with Manager and computers setup with Arabic system locales?
Hence, I would be interested to see whether you experience the same problem with the problem font in any other program other than Manager? Using English Locale (UK) on my pc, I have never experienced any issues with fonts on Manager. I am not sure why Arabic system locale should affect anything, but obviously it does.