I’ve managed to complete the grid without getting the six-word announcement, though I know what it’s about. After solving the normal clues I thought it would be easier to find the ‘correct’ answers, since they were known to be real words, rather than trying to disentangle the wordplay for so many non-words. I have linked the thematic entries to their definitions and they all seem to be correct, so I don’t think I’ll bother to find the non-word version. Unless I have misunderstood something it would seem to be a weakness in the puzzle, splendid though it may be otherwise.
As others have pointed out, this puzzle should remind us how lucky we are to be able to derive so much enjoyment and satisfaction from the series. This site is a tribute in itself, since it would not exist but for the enthusiasm of so many Listenerphiles. (I’m sure there must be a Greek form for this non-word!)