I found a language learning difficulty study/grouping for native English speakers by the US Foreign Service Institute copied all over the web.
Do you know of something similar for native speakers of other languages. I am especially interested in such a list for Asians and Africans, since the list/grouping would be not much different for German or Spanish natives.
I do not need a resource for every language, I am just interested in such for any language.
That is, any 1 such list for a language other than English would be a great answer!