It's not unusual to have to do publishing or design work in languages and scripts you do not understand. In some scripts, if you use the wrong font or app, you can easily generate nonsense without realizing it. So having a native speaker (or at least someone who knows the script) check things can be important. Below are some examples of common pitfalls you may run into. In particular, be aware that MS Word for Mac, even the 2008 version, does not yet support correct display of these scripts.
Arabic script, used for many other languages than just Arabic, can wind up disconnected or backwards.
Indic scripts, used for example in Hindi/Sanskrit, Gurmukhi, Gujarati, Tamil, and Tibetan can easily wind up with letters in the wrong order, overlapping, or uncombined (when combination is mandatory).
Thai and other S.E. Asian languages don't use spaces to separate words, so line breaking can occur in totally wrong places. Apple Cocoa apps can access a dictionary built into OS X that enables them to do Thai line breaking fairly well, but MS, Adobe, and other apps cannot.