I know that Uli pointed out you are struggling with(human) resources and most of the administrating members prefer mailing lists over clumsy web forums- but may I suggest:

You have a great product you maintain with X2Go.Everybody understands this eats up a lot of ressources.

If you created an X2Go Forum you could potentially build up a wider user base. They can then help each other, which makes them happy (and potentially also takes some work from the mailing lists). This again helps a growing user base and vice versa. Potentially a wider user base and more publicity helps you gain more sponsors and donations. And so on.

Further Devs may get further ideas from users, as most users find forums easier to handle than a mailing list.

I strongly believe this could be an overall win-win.

Alternatively, I could offer myself to consider building an (inofficial) forum. I will need help with some admins/moderators though and I will need time, but I like to support good products.

Let me know what you think. By the way I am German as well.