I have no suggestions for a replacement forum, because I've never needed to implement one myself (although I might do that in the near future, if I live long enough). I don't even know what they're using now. I don't want something that interferes with my way of doing things, which a lot of modern software does, with its over-reliance on JavaScript. There are plenty of little things that could make the current software better, if they only cared enough to do it.
Darvond: 2) I don't even know what features they would add that would even make me remember that Galaxy exists?
Downloading old versions of games seems useful to me. Downloading "beta" releases as well. Neither of these would technically require Galaxy, but that's not how they implemented them. Their "offline installer" section only allows downloading of the current release, and I guess they don't bother with patches any more, either (although I'm not sure I remember ever having a game with Linux patches).
3) What are you even using that references Flash? Is it some old addon you never updated for Netscape Navigator 4?
The "grab the freebie" button on the front page (which is the only way to grab freebies; the store page for the game just links to that) doesn't work for me, and hasn't for a while (years?). It claims that it's flash. As I said, even if that isn't the case, there's no reason it shouldn't work in default modern Firefox. On multiple machines, with multiple versions of Firefox. Whatever. It doesn't matter that much to me, since I was only ever even mildly interested in one, out of morbid curiosity.
6) /// using Staging vs the basically moribund Dosbox
I actually disagree with this. I have tried staging in the past. It is not well developed, or at least it wasn't then. Lots of really bad code, e.g. some 32-bit-only code, got in. The documentation was/is also worse. Any undocumented feature is a bug.