Framing language learning as a fun gamified activity apparently works well when you're in the app subscription business, but the jury is still out on whether you can actually reach a reasonable level of language proficiency using an app as your main tool. Me? I'm old school: give me a decent text book, a dictionary, plus something to read, and I'm good to go.
There is, though, something else I added to my language learning toolbox not so long ago: a Kobo Libra 2 with KOReader installed on it. It wouldn't be an exaggeration to say that this combo has taken language learning to a whole new level.