I installed a stable diffusion docker last week, it wasn't too bad, but it also didn't need a lot of config.
I just tried installing lemmybb from the github in it, the container starts, but none of the config is even close it's just not a good candidate without someone checking it out to their own github and applying all the configs and setup.
Someone is going to need to pick it up and give it some love before it's reasonable to add it to unraid.