I'll give the screenshorts for comparision.
Created attachment 83309 [details] screenshot-improper.png The error part has been marked with red line.
Created attachment 83310 [details] screenshot-fixed.png
Created attachment 83311 [details, diff] freetype-2.10-bold.patch
the effect is clear, what do I need to reproduce this ? Is this just with non-latin characters, if not can you provide a screenshot with latin chars ?
The bug can only be reproduced when rendering a char without a real bold font for the corresponding charset in the system(then pseudo font is enabled). Since most systems have bold fonts for latin charset, while most fonts for Asian lanaguages have no real bold fonts, so the bug can be easily reproduced for Asian charsets but is hard to reproduce it with latin chars. And the bug has been fixed by upstream, see: http://cvs.savannah.gnu.org/viewcvs/freetype/freetype2/src/base/ftsynth.c?r1=1.27&r2=1.28
my excuses for the delay added the patch to freetype-2.1.10-r1, please test.