FogBugzPy is now the officially suggested way to use the XML API. It works fine too, but is tied to python 2.7 line.
The module itself is not hard to convert to 3.x but is uses the abandoned BeautifulSoup that is left for 2.x I tried to tweak it for half a day, and abandoned, but it could be replaced with some other html/xml module.
Keeping several vesions of python (+pyQt+else) is quite a hassle, especially on windows. We could just go with the most recent version for everything else, but the FB-related tools need the old one installed also.