I tried figuring it out cold, just to see if I could. I couldn’t. I got E but couldn’t confirm it because I had nothing else to go on.
That was when I checked in with the comments and got the critical clue—compare the code to what Puck and Elvis were saying in previous days whilst under the thrall of the alien siren song.
Fun fact: In the original book Who Framed Rabbit was based on, Toons weren’t animated cartoon characters, they were comic strip and comic book characters, and they spoke in word balloons that the human characters had to read.
I want to know how Iggy got U, the least-used vowel, first. You usually get E first. I got E, but without the hint from Orbsters to look back a few days at what trance-Puck was saying, I’d never have figured anything else out.
October 15 gives a little more information. I think the bottom row was the first indication we had that they were friendly:
Top left: " ‘s / spar / save th" = it’s / sparkle / save the
Top right: “clean / the car / rpet” = clean / the carpet / carpet
Middle: “a.i. d / our wo / now we” = a.i. destroyed / our world / now we
Bottom left: “your fr / tortim / o help” = your friend / tortimer / to help
Bottom right “as a / friend / to hel” = as a / friend / to help