If I recall right, Jap wiki said that the current, active party are what counts. Your sub-party doesn't matter, but if somebody dies from your main party and thus gets replaced with a sub-party member and you now have 4 Wind characters active, whoops, you just lost your bonus. Well, as said by Kitty, no big deal. You'll want to use Garuda until the 45% Wind Elemental Eidolon.

Anyway, has nostalgia tinted my glasses, or did they severely nerf the fodder drops? You get 1-2 silvers, 1-2 golds, and 1-2 plat for first place. And I think you got 2-3 Plat for first place before?
Not only that, but silvers are now R fodder, which I think used to be seeds or SR fodder? And plats are now like 33% T3 Crystals, which I don't think happened last time.