@Hitch: Yep, the K2 is not a good citizen in terms of unicode coverage
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It's much, much better on anything KF8-capable, (i.e., FW >= 3.4), and especially on FW 5.x. Complex script shaping is still touch and go, though, but that's another matter entirely. (Note that I'm speaking solely of eInk devices here, since I have zero experience with anything else in Kindle-land).
Speaking of, FW 5.6.1 saw a serious update of the font rendering engine, so some of the weird quirks w/ custom fonts might have been alleviated on those FW. (Pure conjecture, I haven't updated anything to 5.6.x on my end).