Yes, when building a tournament deck, your playbook must be 50/50 from td's to field goals. Audibles themselves are counted as TD's, so the following would be a correct setup for a deck:
1) 14 TD's
2) 18 FG's
3) 4 Audibles
Note that Audibles are "counted as TDs" simply in that they are not field goals. The playbook rules require that at least half of your playbook cards are field goals. Thus if you have a legal deck that is exactly 50% field goals, and you want to add an Audible card, you will have to remove a touchdown to make room for it.