attention makers of Quick File Rename v5.0 in reply to this claim:
"Full unicode support for international character sets, e.g Chinese, Japanese, Arabic, Tamil, German, Russian, etc. Very cool! Currently this is only renaming application with such support."
namefix.pl has had unicode support for literally ages, Martin added it back in the 1.x days. It can also translate international characters to their english equivalent. According to reports it works fine for files with german, russian and korean characters. Ive yet to hear how it works with Japanese characters, I imagine it wouldnt work the best with kanji.
There are a limitations with perl/tk and unicode atm but nothing that stops namefix.pl renaming correctly. The only quirk i have seen to date is when displaying the renamed file a character will appear as ? in namefix.pl, rest assured the rename worked as expected.