So far I only tried Debian Sid.
I think the issue you described is down to the Xwayland binary. Xwayland should be patched for making it work under SFOS. The patching is done automatically when the script is installing the distro and it requires the source of Xorg. About two years ago when I installed Sid first, the script was able to download the Xorg source and then patch and compile Xwayland.
However, the last time when I installed everything from scratch, the script wasn't able to do that. (This is the issue I mentioned on the first page. I don't think this is connected to sfos version, more likely it is because the source of xorg cannot be found/downloaded.)

Probably when you install other distros, they are installing the default Xwayland binary and that's why you are getting that message.
Have you tried to copy the Xwayland binary from a working distro to a new one? (It is located in /home/.lxc/<container_name>/opt/bin/)