FWIW updating from 3.1.4 to 3.1.5 (and then to 3.2.0) should be pretty seamless.

The documentation does need work, but it's hard to find people volunteering to do it (although a few people do contribute to the docs too and this is something that is always very much appreciated). Any concrete suggestions for improvements are welcome as reports on https://trac.wxwidgets.org/newticket and, as you might have already realized by now, PRs to the docs on https://github.com/wxWidgets/wxWidgets/pulls are even more so.

Finally, asking questions (on the forum, users mailing list or SO) seems to work pretty well for most people.