O.G.:
I'm curious about your Mach lines vs CAS vs altitude.
For example, your chart shows Mach 0.8 at 30,000 is 288 CAS.
I get 304 CAS for Mach 0.8 at 30,000.
In addition, I show A330 Va reaches about 315 KCAS at 27,000 where it intersects the Mach 0.78 Va limit for the aircraft.
You have 0.78 Mach intersecting Va at about 290 KCAS.
(Is it an ISA + x thing?)