Since we don’t author foreign languages, I’m not sure I’ll be much help. For PDF generation with PE, we just ensure that the fonts we specify are installed on the server. We only specify fonts for CJK compositions. Our PDF generation is FOSI-based, so we have separate FOSIs for each language calling out the font families required. A long time ago, back when we were still using SGML, we used Arbortext print composer to generate PostScript and then distill to PDF. Back then, we did have language packs and had to reboot in the proper locale for everything to work correctly. But, we haven’t done that for about 10 years. We eventually found that the only reliable method of generating PDFs with Arbortext were with PE 5.3 patch M040 (or later) and using direct-to-PDF.
I think if you’re using XML and UTF-8 with the fonts you need installed on your system, you shouldn’t have any problems.
Dave