Not all birds have the same intellectual capacity. Believe it or not, in many ways, little Budges are able to talk much better than a Cockatiel. An yet they are both complicated individually. The Mynah bird beats them all, hands down, in being able to mimic sounds, not counting some of those from New Guinea.
In short, Cockatiel gets an A+ for effort. Talking is not their strong point. But their trying will win your heart.
Now write this down:
Little birds learn in their sleep. You have to cause it to dream.
Think of every other wild bird you have experienced in your life time, especially a Wren, then, a Mocking bird.
Their profound similarity is seen in the way they have a pattern of saying the same things over and over, all day long. Now you are the one that needs to think like a bird. If your little one is to have a dreamy relationship with you. Stop training your bird, you are the one that needs training. When you become as a bird to it, dreams will follow. WHAT???
Good question, I thought you would never ask!!
Forget all of the above. But write this down.
"Wolf whistle" non-stop! Every time you come into its presents. All the while you are tending to its cage.
When it begins to wolf whistle, add on "Pretty Bird" When it starts trying to say that, add in, "What Ya doing, Huuhhhh?" At this point your bird is working you. "Wolf whistle, Pretty Bird, What ya doing Huhhhh" all day long till the family is ready to kick you and your bird out of the house. As its dream life explores what is in its ears, it will pick up your sounds faster and faster.
We do that too, really. A translation work That operates muscles goes on in our sleep. From one sensory realm, back to the muscular realm, then to a critical analytical process back to its muscular adjustment training and out again, with its dream life working overtime.