The <characters> tag in the strings.xml file does not work anymore. This causes problems for translations to some foreign languages. A patch was posted on the forums:
http://nolanparty.com/mediaportal.sourceforge.net/phpBB2/viewtopic.php?t=2391

I applied the changes to my CVS build and it works fine. I first tried the Czech and Russian languages without the changes and some/most characters were missing (some for Czech, most for Russian). After applying the changes all characters were there (checked against strings.xml). Note that I applied the changes manually and not by overwriting my files with the files provided in the zip file.