If you're a button, you have one job: to transmit Morse code from the finger to the machine, Morse code representing a complicated POSIX shell command. And also to power down this entire one-button terminal with a 3 second press, power it up on any button press, with a firmware reset if powered up by a 30 second press.
A press of each round button rotates the typing ball accordingly, pressing the space prints the chosen letter and resets the ball to the neutral state. This whole thing should probably be electric lest you'd have to press the space bar by smashing it with both fists.
Now remove the spacebar, combine the two buttons into a single one for "tone" and adapt it to morse code. All the buttons still do only one thing and now there's only one button!
And, you don't have to worry about what to do in the case that someone hits the "rotate ball" button while it's still rotating.
This is literally the type of thing that caused the THERAC-25 disaster (https://en.wikipedia.org/wiki/Therac-25). Experienced users hitting keys faster than the app could process them, resulting in safety features being inadvertantly bypassed.
And, you don't have to worry about what to do in the case that someone hits the "rotate ball" button while it's still rotating.