It sounds like a very new thing. Google has not found a commonly-accepted translation of it in Chinese. In my opinion, 外语旅游 would be concise. Maybe 外语学习旅游 is clearer, but a little too longer to me.In American English, it would be a "language study programme". By saying this, I mean a trip that mostly students take to another country, in order to improve a language. Students can stay in a host family and have lessons during the day. For example, a Chinese student could go to the US for a month, to improve its English, stay in a US host family and go to school every day to have English lessons.
I hope I made it clearer,
Thank you very much for your help!