It probably is a bug, but hard to tell if it's in Symbian or Qt -- have you tried running the same code as a Windows application (not in the emulator)? Are you running your Symbian code in the emulator or on the hardware (or both)?
Be aware that the fonts available on the emulator are likely different from those on the hardware, and both are relatively limited (from 3-5), so "Times New Roman" and Arial may map to the same font. (In particular, there aren't any serif fonts on many of the phones.)
You should file a bug report:
http://bugreports.qt.nokia.com/secure/Dashboard.jspa
(And, by the way, there's nothing wrong with your English.)