Until he improves and gains confidence with his right foot, he'll never become the player we hope for, neither here nor with England.
On the play where he should have won a penalty, Doku played him a magnificent pass, perfectly timed with his run. He was well ahead of the defender, but his choice to control the ball with his left foot and insist on shooting with the same foot cost him time, and the shooting angle narrowed, resulting in that ridiculous shot to the near post that went wide. Alvarez or Marmoush would have ripped the net with their right foot.
I've rarely seen a player so weak or so uncomfortable with his right foot. I'll keep emphasizing this: it's his biggest handicap, this constant desire to get into the ideal position to shoot with his left. Without it, he's completely stuck.