Lots of inconcistencies and illogical decisions. E.g., faeries vulnerable to iron are using iron weapons. Night creatures don't have darkvision. Specialized mages and non-magical commanders for a magical race. Etc.
Also, probably lack an effective endgame.

Thanks for noticing this. Fixed it both for EA and MA Alee.

Also, even if the grasshoppers being uniquely non-sacred is intentional, the unicorns of the sylvan knights probably should be

(for the record, I'm advocating for an increase in the gold cost of the archers to 6 to match the other pixies; I think they are too cost-efficient for 3 gold)

Is it intentional that pixie archers cost half as much gold as normal pixies?

Yes, it is intended

and shouldn't they be stealthy?

Nice mod! Giant Grasshopers (the mounts) are not sacred, is it intended?