Exactly, you just retcon it by saying Soong wanted him to THINK he couldn't, the same way he wanted him to think he couldn't feel emotions, even though we see him clearly doing so as well, and if we assume from his dream program that the intention was for him to graduate into unlocking aspects of himself as part of some growth journey Soong laid out, then all this contradictory stuff about him falls away
True of course, then again from the way Data's learning behavior is portrayed, he might consider that solution "cheating" - sort of
Maybe so. He does tend to get a little touchy about anything that might remind him that he's artificial. (Except of course when it involves processing speed & power, or his heartier physical attributes. Then he's apparently fine being all kinds of inhuman), But yeah... creating a fix that bypasses his natural speech pattern to generate something that is only a mimic of a more human one is definitely not the kind of thing he aspires to, but it was mentioned enough times like it was a real annoyance that if I had been around, I'd have told him. "HEY, just work around it, if it's so awkward for you"
Except, in Hero Worship, Data says "The servo mechanisms in my neck are designed to approximate human movements. I did not realize the effect was so distracting." In regard to Timothy bobbing his head about randomly. He never says whether he means to say that in reference to his "natural" looking around motion or the head bobbing he does when thinking (which is what Timothy's version most closely resembled). He also never says whether this was something done by Soong or that he developed himself. But he is shown practicing laughing and facial expressions on occasion, despite not experiencing those feelings, "to make people more comfortable" if I remember correctly. Side note: his statement implies the hardware itself (the servos) is designed to mimic human motion, though that would have to be a misstatement, since it's the software running the servos that dictates how they operate, especially in conjunction.