Speaking as a total ignorant from a coding perspective. But I guess that wouldn’t be the hard part, considering that most of Duolinguo is just boxes and text inputs. How difficult it is to create a database of competent linguists with an efficient training who can progressively enhance your understanding of languages?
I’ve been learning French on there for awhile now and it’s been extremely effective por moi. They teach you as much French as you would get in a 4 year university program. Plus having an AI powered practice set is like having a teacher who knows exactly what you know and what you need to learn more.
I wouldn’t normally comment on a spelling issue, however, in this case…
Try taking a break for a month and see how much you actually remember. In my experience it was depressingly little, and I’m not generally bad with languages at all.
According to some guy on Youtube, that’s less of a learning method thing and more of a getting over a basic threshold of competency thing. I forget exactly which level he said it was, but the claim was that if you reach at least B2(?) you won’t forget it anymore.
I think this heavily depends on your learning type. For some it may work for others not. What is important that it actually helps some people and these people have no foss alternative around.