Great job, thanks!
Three things I have noticed to fix:
1) Eternal Kindred Highborn and Nobles are blocked from choosing both Magic Weapons and Magic Armor, and Mundane Weapons and Mundane armor. It doesn't say that they can't choose them, just that they lose the Eternal Guard abilities if they choose magic weapons or armor.
2) Branchwraith should have the option to upgrade to a level 1 wizard.
3) Eternal Guard are only core if a Highborn leads the army. It mentions this in the description but doesn't actually change it back and forth depending on who leads your army. Not sure if this is a limitation of army builder or not...
Thanks again
Edit: Found another couple.
4) Wild Riders should have the option to choose a banner worth up to 50 points, but they don't have this option.
5) Treemen Ancients should have the option to be the Army General, but they do not.