11a was my second idea to the instructions, Jono. Curiosity got the better of me and I have finished and parsed it all. I could narrow my earlier observation and define the preamble precisely to make it easier, but I’ll leave it till the morning.
I don’t play Scrabble (maybe I should), but I’m interested to study Quinapalus further.
I’m still kicking myself about Genius 13 (the cat is in hiding). It only occurred to me today that the number of the puzzle was significant. There are only about 20 words of 13 letters which don’t have a repeated letter, and the only common (?) ones would be UNPREDICTABLY, SUBORDINATELY and COPYRIGHTABLE, so I should really have twigged that the top row was key 🙈