This is not a bug report section. It is in the main section of the K4 module.
It is not changing opinions, it is a typo. Nothing above 750kph was actually tested. It was extrapolated and the dotted line supports this.
And I never said 109s couldn't do 750kph. That's the max permisable speed for safety, but Kurfurst has shown data that proved it was moved in later models to 800kph, which I accepted. Still, no document has shown test data on roll rate at that speed.