Cimorene

Long-time reader, first-time commenter. Hi! I hope you don't mind if I comment on the qualifications of EFL teachers.

I think that, to qualify for teaching EFL to adults, you'd need a university degree in English (or English Philology, as it is called in Finnish universities) plus pedagogical studies. I.e., the same that Finnish teachers of EFL do. As you wouldn't be teaching children or teenagers, I think you could do the pedagogical studies either at a university or at a university of applied sciences (= ammattikorkeakoulu). (If you want to know about the differences between those two pathways, just ask me.)

While the pedagogical studies are usually in Finnish (at least as far as I know -- I haven't actually studied them myself), I think it would be possible to study English Philology without needing to understand Finnish, depending on the requirements of the university in question. In my own studies at the University of Oulu, there were only a few courses that would have presented problems. And as far as I know, at least the University of Helsinki makes provisions for students who don't know Finnish.