I struggle with these type of balls whether it is a rally ball or slow moonball like second serve. I set up nicely, get into the position with my regular SW forehand and bang into the net! Next time i try to adjust, oops wild long... Bloody annoying. How to find the middle ground guys?
I was hitting average rec overheads often too sharply down into the court. They would bounce short, high and slow and become a set up. Too many also in the net.
I asked an instructor. He said that the distance between my body position and the dropping ball was probably too great at impact. When the racket contacted the ball, it was too closed. He stood in front of me and held a ball high and asked me to put the racket on the ball. I did. He moved the ball farther away, I again placed the racket on the ball. The demo was very clear as to how the body position affected how closed the racket face was at impact.
My overhead problem was positioning and getting set too early and not keeping my feet moving. This awareness fixed the problem immediately. From then on if I hit a ball in the net, I would remember this and be aware of my positioning.
In your case of a high floating ball, the ball is dropping faster than a groundstroke with pace, the height of the ball at impact will be less certain. You sound as if you get in position early and set up. Try keeping your feet moving, small steps, as you look at the ball.
A second basic issue for a forehand is how you handle high short balls, the racket face angle and stroke. It's different than for baseline strokes. You don't need much/any topspin for a high short ball, options? use less topspin, use more sidespin? Heavy topspin is a good option. Grip change for short high balls? With SW grip racket face angle changes with impact height. ? Study some high level points and see how the their strokes are different, especially upward racket motion for topspin. But you can't see the grip very well.
Probably high speed video, side view, would show you what is happening is a short time especially how closed your racket is at impact. Check ball watching and when you stop positioning. Video in direct sunlight with high speed video.