I would suggest adjusting B24 bomber by reducing its cost more and increase its strategy bombing ability. Right now the bomber is kinda in an awkard status that it basically has the same cost as B17E but gets only longer range and doesn't have any advantage in its bombing ability. In history B24 is the mostly produced bomber for the US because it's cheap, able to travel longer, and able to carry much more bombs than B17. But yes in the great cost of its survivability. Hope this helps.