Bit late in the day asking for help, but I can't quite finish this. Grid is filled and highlighted as required and I have one of the titles formed from the 'overlooked' letters.
This title is 3, 6, 4.
Which leaves me with four known letters, and three I can't work out from the clues - even though I have the answers. Don't want to say what these are in case I spoil it for anyone still doing the puzzle, but wouldn't mind a hint with the mystery title.
Thanks!