Cool to know re: 3.1.5, but I don't think I'll need to dig into it as Dolphin upstream moved to Qt, and eventually, hopefully, Slippi just mirrors that.
And yeah, I hear you on the people issue... open source is sometimes a thankless job. Overall though, great job on wxWidgets so far - I really do think it's an underappreciated project.
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.