You showed how easy it was to add a keypress control with color, even I could figure it out! ;-))
I was thinking to counterbalance the left cue ball for selecting Left and Right English, at Right bottom corner, use for Angle and Power numbers then use +- or {} or [] <> some natural pair keypress for increase and decrease angle and power should be as easy to change as the Left right arrows for English (save up and down arrows for cue ball of course).