Hello jigjag and stephen53
I was just trying to give a context where the superlative and comparative senses of flatter/flattest - truer/truest might be considered interchangeable ('the **** of two surfaces'). I may be completely wrong because I don't get too bogged down with grammar in crossword puzzles, but I think the setters and editors do, and if they've made an error here it's a bad one.
I could even try to defend the west/north issue, because I think I've seen this debated before. I believe it's a crossword convention rather than a rule to use N-S in clues for down answers and W-E for acrosses, but we always construct words in English reading L-R. The direction for how answers are to be entered is given under the headings 'Across' and 'Down'. In this respect the setter has given us a correct clue for the construction of the word required, and 'Down' tells us how to enter it.
I think the wrong entry length is probably just a typesetting error.