This question already has an answer here:
I know that is not allowed to create new languages for interfaces, but can we create another language stackoverflow site with English interface? So, all Q/A in another language, but interface is in English.
EDIT: Thanks to James Jenkins for his answer. I would like to refine my question. Here i'm interested in possibility of creation stackoverflow site in another language. I know that it is possible to create such site for language learners, but that's a special case. Can this practice be extended to sites like stackoverflow?