DO NOT try to explain any of that stuff to children. They will soon come to associate tennis with chores or even worse learning and lose interest. As for your dilemma, have you thought about physical training rather than theorizing?
You will find it works much more effectively and the body does automatically compensate after a small period to adjust to what the mind is telling it.
For example, it you are hitting the ball too short with too much spin, make the stroke LONGER for more depth, don't hit it harder as you will create more racquet head speed and spin and it will drop shorter. If you are hitting too long, try coming a LITTLE more low to high.
The body will do what you tell it to. It may take a while to become automatic, but the body is a pretty clever unit. Trust it.
Never give up.Never,never,never,never.