counts include common and dark speech. stats did not change till a new language was at 100.
With 6 at 100 it was 19AC 328hps 317 Mana
With 8 at 100 it was 26AC 457hps 441 Mana
with 10 at 100 it was 34AC 586 hps 565 mana
with 12 at 100 it was 42AC 715hps 690 mana
Dragon, thieves, combine and other odd ones did not matter. It was only for the actual player races.