Russian Letters on iTunes
I'm experiencing this same problem; I tried adding Russian in System Settings to no avail. I'd like to add that copying manually the files' names as they appear in Finder to iTunes will let you paste the names by cyrillic letters to the songs.
So if what chscag says is true, that it's an issue of fonts, is there any way to fix this? Obviously, I really do not want to input these names manually.
(I know some fonts don't support cyrillic, however, it doesn't make sense that either the default font in iTunes or OS X files are one of them, since a name using the cyrillic alphabet is maintained in both. I'm guessing it's related to how the importation feature in iTunes is programmed.)