Read this a couple of years ago but The uke is the host family for the exchange student the Seme I think he was french but he had long hair. It was just a one shot but I really liked the story

Hmmm, not exactly the same but following stories come in mind
French foreign student, but no host family- Mobile sweet honey Chapter 5, Lets get romantic
Host family but not french student, rather some foreign prince- Pet wo kaimashou Chapter 5-7
Host family but tribal student- Raion Gotoki no Kuni Kara and Ore ga Iinchou no Mesu ni naru Made Chapter 5-6
Transfer student and french neighbour-Ame No Mukou, Kimi To
You can also try the following tags
Excahnge student
Transfer student
French
Foreign exchange student