It's still not learning, it's verification of existing knowledge. It might be more fun than taking tests, nevertheless you cannot learn knowledge by testing knowledge, you can only verify it. Only if the user answers correctly you might consolidate the already existing knowledge.
I thought about that probem as well, and i think an important aspect that you could improve is by showing the correct answer much more visibly.
Right now it's hidden in a corner (iirc), so that i can barely see it. By showing the task and the answer next to each other when doing it wrong, the players might learn something of it.
What i typically recommend my students is to try to transform a learning task in a way that you need to apply a skill, without needing to do the skill itself.
For example playing english text adventure games is a very fun way to learn english. Players need to figure out what to enter using the keyboard and they use classical methods of figuring out the correct content (dictionary, translation) and they still have fun doing so. Even if it's hard work (not so much anymore with deepl etc, but back in the day it was). This can be applied to tons of tasks. - make sure you are not cheated when trading in a game. - keep up your reaction time by playing race games (a very good thing for elderly who want to keep theyr driving skills) - train your dictionary skills in scrabble. - ...
I think it is fair to call it more practice than learning. I hope to add more games in the future that focus on the learning aspect of things. However, as a beginner, I still find that it helps me learn new words. If I continuously make the same mistake and receive feedback on my answer, it eventually makes me learn what is correct.