Two things I hope they've improved with the app:
1) I'd like to be able to play a full 15-to-20-minute game. In the last edition, the main game ended after three rounds--we don't get to see the $5K!
2) Computer opponents aren't always the brightest. They'd sometimes call a "Q" or something near the start of the round.
I agree with you on the timed game option. For them to put so much emphasis on the $5K space in their marketing, it's kinda a bummer that we don't see it in the actual game.
Regarding your second point: are they doing this on hard mode? If so, my only explanation of why that happens is that the game may have probabilities for picking a right or wrong letter like so:
Easy mode: CPU has 40% chance of picking a right letter.
Regular mode: CPU has 60% chance of picking a right letter.
Hard mode: CPU has 80% chance of picking a right letter.
Once the program sees that the computer player has landed on a valid wedge, it runs a random draw program based on the probabilities above to see what kind of letter the CPU player chooses. If the random draw comes up "right letter", the computer chooses a random good letter from that pile. If it comes up "wrong letter", the computer player chooses a random letter from the bad stack- hence why you would get computer players choosing X, Q, and Z more often than not.
I don't code computer programs (and never have), so if my statement above seems illogical, let me know.