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.