Cauldron has been discontinued and Sponge is not released yet/still in beta.
Also we only add mod packs in their official configuration as they are distributed by the author. That means that we don't change the server version to e. G. Cauldron. This would decrease the stability of the mod packs.
We already have some modpacks which run with Cauldron out of the box.
Site :
http://minecraft.maeyanie.com/cauldron/
