FMG is correct as usual the pieces have the match the OOB colors and the dice. This is very important.
Once it is feasible they can consider other colors.
The French Army does not wear blue.
The USSR did no have red uniforms.
The new AAE40 colors will have french as blue and FMG must match these. French are always colored as blue historically anyway.
USSR should be colored original milton bradley brown, which is what has been used in most wargames.
If you colored every army according to its uniform, then every color would be too similar as being practical.