Can't you just take the Channeling 2 promotion away from the arcane units? I thought you could set promotions on an individual unit level, rather than just a unit type? Alternatively, go back to the FFH system; take channeling away as a promotion, make tier 2 and 3 upgrades start with channeling 2 and 3, respectively, remove channeling as a selectable promotion for all sorcery units, and require literacy and education to build the tier 2 and 3 casters.
But even level 1 spells are too powerful/come too early at the moment.
I don't know that watchtowers in forests are too powerful, the AI is weakened by building so many of them (yeah they give some commerce eventually, but are usually weaker than cottaging would be). I know they upgrade slowly themself - do they upgrade faster if you work the tile?
Is there a way to make them only give defensive bonuses to the civ who owns them (ie whose territory they are on)? That way you can't shelter in them while advancing with a StackOfDoom.
It does have the interesting side-effect of preserving some forests for AIs who would otherwise clearfell everything, so they have a bit more health which they are desperately in need of (unhealthiness hurts much more in this mod, for a number of reasons. Marshes in particular).
Note that barley and pipeweed (+ happy - health bonuses) are almost useless. The health cost hurts nearly all your cities (which tend to be unhealthy) while helping only those at happycap. I tend to cottage over them, and just treat them as a regular tile with a +1 food bonus, or to build the brewery on them but not hook up the resource.
Another idea; there are likely to be problems on the real warhammer map because civs are so far apart, and so much of the map is empty. It would be totally awesome if you could rig up an existing earth map (just add the resources and start positions) with appropriate matchings; Empire = Germany, Bretonnia = France, High Elf = England, Kislev = Russia, Lahmia = Egypt, Vampire = Balkans, Tilea = Rome or Greece, Hung = mongols, Ind, Araby, Amazonia, Cathay, Nord obvious, HobGob khans in western central asia (east of Urals), - maybe put dark elves and wood elves in north america, some chaos/orks for persia, carthage, africa. I would totally play that.
By the way; in case this all sounds like criticism, I love some of the things you have in the mod. In particular, the high elf unit art is awesome (and Bretonnian knights are cool), and I love how you've implemented cavalry, chariots, archers, catapults/cannons. Cavalry that rule the open plains but you can hide from them in forests. Ranged attacks for weakening stacks (if only AI would use them?).
(it has had it for 58 turns now). I had three with the bug promotion (unfortunately 2 of them killed themselves via a getem result later 
).
