Zonton (if that really is your name
) as a fellow leftie I feel your pain! It is refreshing for a change not to have to convert everything I read from a rightie's point of view.
You are right that every change you make potentially changes something else. My experience is that you are not going to find one magic bullet that solves everything, but you may well find the one thing that causes the majority of the problem. If that is the case, then other issues become apparent. For instance, you might get the alignment right but then have a problem with not having a smooth transition so you miss just like you did before, and then you have to work on those things to continue your improvement.
To illustrate the point further, I'd say that you've made certain conclusions that might even be wrong. You said that you stroke back off line and as a result you twist your wrist to bring it back in line. What if it is the other way around? Consider this: Maybe you tend to twist your wrist as you come forward and that is causing you to bring the cue back off line, which would be the opposite of what you think is happening. I think every player tends to curl the cue under since the fingers wrap around the cue from one side. When you jab the stroke or hit hard it is natural for the fingers to tighten and curl. Your brain is clever so it will figure out how to pocket balls when you are twisting the cue. Maybe in your case you learned to take the cue back cockeyed to compensate. Just food for thought. Everyone understands that the cue should not rotate as you shoot. That is easy to see but not always easy to fix. I would make sure you are not twisting that cue AT ALL before fiddling too much with your vision. Maybe you'll get lucky and things will fall into place when you stop curling the wrist and/or fingers. Shoot slowly at first and do what you have to do to pocket balls without twisting the cue.
I'll give you one example of what I was dealing with as it might help. I found that when I took the cue back and it stopped before going forward again I was pulling the cue in toward my body just a little before I went forward again. It was like clockwork and amazingly predictable. Pull back straight, pull cue in maybe a quarter inch, then stroke straight forward. This worked fine for years but at higher speeds things broke down as it does for most people, and I felt this "swoop" had to go. So what caused me to make the swoop? It was my visual alignment. When I got down on a shot the cue would look straight through the line of aim but in reality the butt end of the cue was too far away from my body. Again, it LOOKED perfect from the half of the shaft forward that I could see, but it wasn't. My brain learned to pull the cue inward onto the real shot line just before I came forward with the cue so that the ball would be pocketed. I personally don't think anymore that having the cue "look" lined up before the shot is all that necessary. What is necessary is that the cue IS perfectly on line and perfectly stroked. Whatever that looks like to you will become the new normal and like second nature, IMO.
I'm realizing that I can go on for too long here so I'll cut it short. IMO, the single most important thing I did was to get an app like Coach's Eye to allow you to draw lines over the video for reference points. You also need to be very precise about getting a straight in shot and a camera angle that is exactly on this line. If the camera is off line it will fool you (use the grid lines to help with aligning two balls). You don't need lasers etc if you have that. That's assuming you are working on this yourself and not getting in touch with a good instructor. I think, personally, at the higher levels of play you need to figure out things for yourself, but a check up with an instructor that you trust is a good thing.
Disclaimer and fine print: I am not an instructor. I'm simply relaying my experience with the stroke.