I enjoy this app!
Being able to sort articles would be nice! Maybe by category or level.
I also think maybe more vocabulary translation, or even some grammar.
Also when I went to change my level you can’t see the unselected options. (So you have the six options, only 1 of the 6 is visible.)
Another feature might to be able to save words to review later.
These features aren’t necessary, but might make the app better. It might also make people keep coming back!
As a summary: the core app idea is great! I think the grammar could be more complex for the higher levels. A sorting or category system might help. More vocabulary or grammar translations.
These are just things to look into! I know just how hard coding can be! Especially depending how many people you have! Though this app has great potential!