There are twenty Chinese and Japanese "dan level names" in this article's table, all of which, I think, should be aliases of this page. Currently it seems that only shodan is.
Is there any reason for them not to be made aliases? They don't have their own articles. I think that in the rather less Japanised environment of Go in the 2010s and 2020s (as compared to the 2000s and last century), many people probably don't know what a rokudan or hachidan is off the top of their heads. And the Chinese names are certainly obscure in the West.
Making them all aliases would be not good, since the meaning of "dan" is different than any of them. Also it seems that "shodan" should not be alias of "dan", since meaning is different. I guess redirection would be good trick, however i am not sure if SL have redirection mechanism like wikipedia.