I have been running Shimano wheels/cassettes with Campagnolo derailleurs and shifters for years. To recap, here are the combinations that work perfectly for me:
Shimano 9-speed cassette with new (rounded hood) Campagnolo 9-speed shifters and old (8 or 9 speed) generation derailleurs.
Shimano 10-speed cassette with Campagnolo 10-speed shifters and old (8 or 9 speed) generation derailleurs.
The math works, and it works in practice.
I'm excited to learn that the new generation Shimano rear road derailleurs have an actuation ratio of 1.4:1, or the same as the older Campagnolo derailleurs. I am tempted to buy a Tiagra 4700 unit cheap to plug it into one of my mixed-marriage drivetrains. Or perhaps I'll go with one of the new Microshift derailleurs.
I have a many-lifetimes horde of the older Campagnolo derailleurs stashed away for my mixed drivetrains, but this is something new..