English as a first language

I’m having a lot of fun helping Nate learn to speak and watching him communicate. One of his more perplexing pronunciations is “lion,” which he learned perfectly, then switched to “liney.” So I figured we’d work on it.
“Nate, who’s that?” I said, pointing to his gold teddy-bear lion.
“Liney.”
“Yes, but it’s not liney, that’s lion.”
“Liney!”
“Nate, can you say lie?”
“Lie.”
“Good! And how about yin?”
“Yin.”
“Good good! Now say them together. Lie-yin.”
“Liney!”