I think after balancing out two hoburg nations already Sombre had enough of the little folk for a while.
Maybe we'll be able to include them in another game, I don't think that there is enough time to have them in this one. Arga Dis is free for you to take, yes. The link on page 2 only features the nations which we used in our first mod nation game, NeoXekinima.
If you want to playtest Arga Dis, download them and their CBM version if there is one, and use them with the CB enabled.
P.S.: Actually, if Sombre says that your hoburgs are balanced enough already compared to the other nations, then I guess I can include them. But if he needs one or more days to balance them out a little, there won't be enough time.