Thanks for the feedback. I've decided not to make any nerfs/buffs.
If I were to make a small nerf to the most popular class, it might end up having the opposite effective, and more people would join because it was perceived by other players as being the most powerful. If I were to make a large nerf, then those players might simply switch to the second most popular class, and I'd have to nerf that class. As for buffs, they are no longer necessary. More people have sent in their choices, and every race now has at least 2 players, which means we'll see a pretty good variety of decks.
With recent sign-ups, the largest race has about 30% of the players. If it was 50%, I would nerf it, but I think 30% should be fine. I'd prefer 20%, but that would be nearly impossible with 7 races. I realize, however, that it wouldn't be very fun for players to face the same race over and over again. Thus, I've made an addition the rules that states that players will not battle a race they have not yet played, if possible. Thus, as long as no race has more than 1/3 of the players, then nobody will play the same race for both Rounds 1 and 2. However, it's likely that players will have to face a race for the second time in Round 3 or 4. I have edited the original post with a full explanation of how the pairings are made.
Lastly, since the question has been asked a few times, I would like to restate that off-element pillars and pendulums may only be used if they are on your list of Support Cards. Players are free to change their selections up until the sign-up phase ends.