http://bugs.winehq.org/show_bug.cgi?id=58942
--- Comment #3 from Rafał Mużyło galtgendo@o2.pl --- I mean DX 5.1 would be horribly out of date even by Windows standard, so while that doesn't 100% exclude the possibility of native directx having *some* positive effect, it makes it highly unlikely - even more so that being a necessity.
Going by the sources, the debug channel for that function is 'bidi' (bit surprising, but whatevs), so you might look at that, but is sounds more like a missing font problem than a directx one.