Yes, the intonation is very unusual, doesn’t make sense..I trained as a speech pathologist, and his speech and language abilities are definitely concerning. I would be expecting a 3 year old to speak in full sentences with reasonably correct grammar, but he isn't - at least not on camera. His speech is pretty unclear, which wasn't helped by Colleen reinforcing pronunciations like 'dar-dar' for car. He also has really unusual intonation - like he's asking a question every time he speaks.
I think he’d have self-corrected if exposed to other children, so it’s really unfortunate they keep him so isolated