The ordering (shaping) of characters in khmer doesn't seem to be correct. Do you support complex rendering in PrinceXML? If so, what shaping engine to you use? usp10.dll, pango / graphite, icu or something else?
In Prince 7.0 we've added support for Arabic and Indic scripts (Hindi/Devanagari, Bengali, Tamil, etc.) We have not yet added the shaping rules for Khmer, although we can certainly add it to the development roadmap. We use our own OpenType shaping code.
We don't support graphite fonts at this time, just OpenType.
Thai mostly works, as it does not seem to require any special character ordering, although it does require custom line-breaking which we don't do automatically yet. Other South East Asian scripts requiring reordering have not been implemented yet.
If there are particular scripts you are interested in, expressing that interest may help to move them up the roadmap.