Right now available Energy is displayed as "X / Y"
X is the amount of energy actually available, be it from normal energy, trophy or reward additions, or purchased energy. X works perfectly.
But Y is stupidly useless... it tells only the total of normal energy plus trophy adds, and doesn't change.
I propose that if I purchase a pack of 50 energy, Y should increase by 50. Similarly, if I cash an energy reward, Y should increase appropriately.