I see what you mean I think, that extracting the final phrase and reusing it in a different context leads to more problems. I was thinking about the possibility of not picking out the final part of the message, but really I suppose it's more likely that someone would miss the full message itself (but I think in post 1.17 versions you've added more letters to the "notes" part which should make it clearer). I'm probably concerned about nothing. :)
(Yes, I had the whole message and was being unnecessarily cryptic about spoilers.)
My son finished this evening and found the final leftovers (then struck off the "extra" A). Interestingly he didn't go to highlight it in the grid, but he did write it in the final slot on #12. He also enjoyed it very much.
Fair enough on the 144 vs 150!