Something I didn't mention in the video is that I had to tweak the positioning of certain letters due to common digrams in English. For example, I originally had "v" as a right-hand thumb key due to its frequency as a standalone letter, but some common English words have the digram "ev" ("ever", "every", "never"), and "e" was also a thumb key, so I remapped the "v" to my pinky to make those words much more smooth.
To do that same process for musicality would be challenging since your average English sentence contains so many different letters. I would probably do something like assign each letter a set of sounds, then pick one of those sounds based on the rest of the sentence.