He is indeed older than the target of those pages 😉 But it seems his interest has sparked again and his duolingo profile is progressing further, I keep him in my lap while he does the lessons, and he likes seeing his avatar climb the score list.
Considering how easy it is for english stuff to end up in front of him, I am confident that as soon as his vocabulary is large enough he will be even more motivated because he will notice it's a useful skill.
I am not at all opposed to videogames even, the old SCUMM adventures are visually pleasing and full of interesting clues