Not quite sure the complex font-shaping thing is theoretically handled properly at all and/or fixed by the Fonts hack on the K4, since its fontconfig (and thus KF8) handling is rather hackish and crude there, but Doitsu probably remembers that better than I
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It's handled as a rather dirty hack in the FW 5.x fonts hack (related to how the fallback font is handled), and I never could manage to make it behave properly 'on demand' for a specific family (without making it globally pass as the fallback font, which is the current workaround), which explains why embedding doesn't help on a vanilla device. Thanks for the tests on FW 5.6 though, since that was going to be my next question, as that release saw some significant changes to the font rendering stack
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