When a QTextBrowser widget (probably happen with QTextEdit too, but I didn't test it) contains mixed Left-to-Right text (English) and Right-to-Left text (Hebrew), there are rendering issues with the characters around the transition point from LTR and RTL and it renders the characters around it as square boxes (usually in the English characters that are around the Hebrew characters).
It works fine on iOS and desktop platforms. It's not a font issue, as the characters rendered otherwise are correct, plus on my real app where I first encountered it, a custom DejaVu font is being used and is the same font used on the iOS and desktop platforms, which work fine. So it seems to be something with the Android port itself.
Attached is a sample app that exhibits the issue – just a QTextBrowser in a generic widget set with rich text that has mixed LTR/RTL rendering. A screenshot of the Android rendering (on a Google Nexus 7) is also attached.