Cockpit language never applied to Radio Comms, ever - rather it applied to the HUD and Cockpit Text Language (if applicable to an aircraft)
Russian Voices for Russian Aircraft, is a design choice and it had been that way since Lock On 1, until about 3 versions ago. People complained (as did I) and now it is set back to the way it was.
Are you saying that if you fly an F-15 on the red coalition, other F-15 wing-men Speak in Russian?
Nate