The Kawasaki naming convention doesn't make it easy, especially as there are both the H2 and the H2. It's a bit like Honda reusing the Silverwing name; originally for a faired CX500 and later for a scooter.
Agree with your comments on the Z650RS and Z900RS. And of course things are confused as there's a Z900 and Z900SE. Oh and Z900RS SE...