For example, regular zombies are created from zealots, and plague-ridden ones are created from regular swordsmen. The same applies to cyclops: regular undead rise from blood-eyed cyclops, and death harbingers rise from regular cyclops. This is an obvious oversight and should be changed.
Also, golems and "divine" creatures (unicorns, angels, and phoenixes) should not be converted into undead either in the converter or when joining, when the necromancer has learned the "herald of death" ability. Currently, this is not the case for some reason.
I've noted this! I'll try to figure it out.