What string to be displayed and what font is going to be used is definable in the welcome.xml for each language.
Sample welcome.xml for English
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!--$Revision: 19319 $-->
<!-- strings 30000 thru 30999 reserved for plugins and plugin settings -->
<string id="30000">English | English</string>
<!-- strings 31000 thru 31999 reserved for skins -->
<!-- strings 32000 thru 32999 reserved for scripts -->
Please refer to the wiki page for installation and setup
You need to choose one "super" font as detailed in the wiki. I made 4 fonts (any one of them) will be able to display full range of characters for all languages supported by XBMC. There is no license issue of them. The size is considerable small (4MB or 8MB).
Please note that as soon as the script is launched, it will not give up if the user changed its mind to cancel it, i.e. press "esc" key will only bring another select screen until you choose one.
This script should work on all platform, but I only tested on Ubuntu 8.10.