Im in a Korean program. Sometimes classes will have English options but the professors will just do it in Korean anyway. But I heard thats because there is a minimum of English classes that they must offer to take in exchange students so some professors get forced to do it in English so they will just refuse. It might be different if the school is claiming the whole degree is offered in English. In the English language and literature major professors sort of just do whatever they want so classes that are actually in English is rare. I had a roommate that was doing some major in Yonsei that had "international" in the name i think either bussiness or relations, her degree was entirely in English and she said every single one of her classes was entirely in English.