It is a very useful application, indeed. However, I would recommend bigger letters and an option to switch the language to English.
And I for myself don't feel comfortable, when other people touch my Touchscreen. What about the arrow keys and the B-Button? I would recommend to use these Buttons too, so that the players can push these to activate the other player's clock, hence they do not have to touch the Touchscreen.
Thanks for this great tool! Ryoji?