When you are typing: you don't have to wait for the "right time" to hit letters.
There are plenty of games out there which require you to hit a button at the exact right moment.
I don't think it really applies to typing, and making it a timing issue for 26 characters, some shifted, and also punctuation, makes this more complex than many of the music games, where you need to play the right note at the right time. While a piano technically has 88 keys, the player usually only has to deal with 1 octave or less.
What I would suggest, instead of random letters, is to have the player type something meaningful.
Also: having the letters move left to right means the player is reading right to left to "shoot them down", but in English, we read left to right.
Conclusion:
Have meaningful sentences scroll from right to left, properly capitalized, and with correct grammar and punctuation. This way the players get familiar with all aspects, not just typing.
Of lesser importance: the screen changes are a bit off: your party is effectively hidden until you move further onto the new screen.
The buildings are all closed at the start, no means of preparing for battle.
You have 4 members of the party, there are 4 critters in the battle room, but this seems irrelevant to the actual battle. Maybe try to make some sort of connection?