A year later, I think I've found the definitive solution to this text rendering issue without having to resort to an old version of Wine. If you look at the Wine FAQ (http://wiki.winehq.org/FAQ), section 10.12.6, there is a blurb about missing or corrupt text with QT applications. The fix is to apply a registry edit as described in the FAQ. Put the following in a file (e.g. norender.txt):

[HKEY_CURRENT_USER\Software\Wine\X11 Driver]
"ClientSideWithRender"="N"

and then run WINEPREFIX=/path/to/MoI/base/wine/directory regedit norender.txt

This sounds like it changes the font-rendering method. This fixed the problem for me on Wine 1.7.50.