My first thought was how unique the color combination is for that set. The yellow and pink accents gives a strong contrast to the black alphas.
The only criticism I have would be to make the arrows on the backspace and enter key smaller. The "+" needs to be smaller as well. Also just my opinion, but I think you should choose a rounder font for the hirigana sub legends, since it clashes a bit with the roundness of the English letter font.
Overall, well done and best of luck in making your set