I have had a full grid for some days with no idea about the endgame. I saw the pattern in the extra words but no bell rang nor penny dropped. I don’t have Buddy’s excuse of an ocean and a continental culture separating me from the theme but I am nevertheless almost as far removed from acquaintance with what is needed as he must be. Whatever, light has finally dawned and I can see that it is all very cleverly constructed.
I went parallel for word one - just to be contrarian.