I hope this doesn´t earn me the reputation of a bean counter, but anyway:
my figures are correct, please check out your timetable more accurately:
yes, the last row on the 320 is called 27 - however, 13 and 17 don´t exist on any LH aircraft, and 15/16 is one row (15 on the left, 16 on the right) - 27-3=24;
yes, the last row on the 321 is called 35 - subtract 13 and 17 and consider that 11 comes right after 8 - 35-4=31
Concerning leg room, you´re right that Y and C don´t differ. The difference is service and the 5 abreast seating.