OK, so according to my math he's 3 (?). Sounds like he's acting like a 3 year old
He's probably paying attention to what you're interested in when there's no one else around to pay attention to, but when the other 2 year old is there, he wants to play with her.
FWIW, we took our kids to language lessons when they were 3 and younger, but we were in a group setting with usually around 4-6 kids. The lessons were given at the teacher's house, and everything was play- or craft-based in some way. There was a lot of movement and kid-exciting activities, combined with a treat at the end of each class. Lots of singing kid songs too (in the other language of course!). I think my kids paid as much attention to the other kids as they did to the teacher, but the language lessons sunk in because although each language had a focus, the teaching done through a lot of talking while the kids were working on something with their hands. It wasn't immersion in the total sense but it was somewhere in between immersion and explicitly practicing words.
If we'd been going to just-mommy-and-me lessons for awhile and then another 2-year-old showed up, my kids would have been all about playing with the other kid!
Best wishes,
polarbear
