As promised, attached here is the 5-language localization package (via U.F. v 2.0) for Sony firmware version 1.1.00.18040. The menu language switches between English, French, Spanish, German and Russian.
If someone prefers a ready-made image with built in Cyrillic-enabled Unicode fonts (the default Sony fonts only supported Western European characters), you can download it
here.
To switch between locales go to Settings->About (or whatever it is in your language) and press 1.
Any questions/problems - post here.
Known issue: some messages are not translated - either because I was lazy, and I thought in case of emergency they could easily be understood without translation, or because I haven't yet figured out how to get to them.