Something that's not specific to Wild Mana, but carried over from base FfH. And not a bug, but something that strikes me as not quite right:
The Khazad and Luchuirp have as one of their unique units the Dwarven Druid, which requires Neutral alignment. Most of the Luchuirp leaders are Good (one is Neutral). The Khazad have one Good and one Evil leader (the rest Neutral).
So if you start as a Good leader of the Luchuirp or Khazad, you have to convert to Octopus Overlords to build the Dwarven Druid. Not a bug, obviously, but the flavor doesn't seem quite right, i.e., having to convert to a religion of Asylums, Lunatics, Krakens, and water-walking demons (Stygian Guards) to build a unit whose magic relates to the Earth. (The Evil Khazad ruler would have to convert to RoK or Empyrean, which doesn't seem quite so strange.)
The easiest solution would probably be to remove the alignment restriction from Dwarven Druids. If you think that would be unbalancing for the Good and Evil leaders, you could block the Khazad and Luchuirp from building Paladins and Eidolons, although I'm not sure that's necessary.
Alternatively, you could make all the Khazad and Luchuirp leaders Neutral, but that would be a bit dull, I think.
P.S. On a side note, "Grove" doesn't seem to quite fit units whose power relates to Earth magic (Crush, Earthquakes) as opposed to the Nature magic of the standard Druid. Maybe a replacement building for the Dwarven civs, e.g., Stone Circle, Megalith, Dolmen, etc.?
EDIT: Found a cool word on wikipedia for a possible Khazad/Luchuirp replacement building for the Grove: Cromlech. A good Celtic word (there are other references to Celtic mythology in the mod, e.g., Oghma, Ceridwen, Amathaon, Govannon), plus it sounds like a word you'd find in Dwarvish, no?