Yeah, I personally think that the Moon Sow campaign focused too much on the Horned God.
You can tell that the writers of the comic Slaine are Wiccans too.
(Maybe if they had some Celtic Scholars involved, there would be more variation in the religion portrayed)
I would have liked to see more of a Pantheon than focusing on Cernunus and Danu.
I agree that the whole campaign (indeed, the whole setting) would be better served by drawing more heavily on real world mythic/legendary elements, rather than the hodge-podge of pseudo Celtic, Gaulish, Anglo-British, Norse and Saxon trappings presented. Now, to be faur, I am no fan of the comics, was not even aware of them until I purchased the d20 Slaine RPG many years ago, now, and will, no doubt be branded a Philistine and ignoramus.
Be that as it may, I've finally decided to tackle the Horned God/Moon Sow campaign, but not without significant revisions to the setting and story. In MY Pseudo-Celtic game, the Tribes of the Earth Goddess are actually descendants of the Milesians, who conquered the Tuatha de Danaan and drove them to Tir nan Og. Fomorians still raid occasionally from Tory Island and Lochlann, the Fir-bolg cling precariously to their diminishing holdings in western Eriu, and a wave of new migration from Gaul threatens the fine balance that exists among the Earth-Goddess tribes. There is no Midgard, instead there are wild savages in far-off Germania (for want of a better name), there are no flying coracles, no phogors. Titans (Giants) exist in Albion, but their numbers are dwindling.
Now, the campaign may prove too mundane to sustain, and I may well end up reitroducing some of the comics' elements, in which case I'll dine heartily on humble pie.