Recently I gave units new health values, and shields to some, along with raising the damage dealt by the weapons.

For the most part this worked, but there are some problems. For one thing, one of the Wampa units I have doesn't have a shield (being just a Wampa). I set its health as 100,000. However, it takes only one 10,000-damage bolt to kill it. Why would that be? I tried setting it's health type as "Animal" and adding the line AnimalScale = "0.05" to the ordance's ODF: no change.

Did you remember to change the MaxHealth ODF property too?

Yes, I changed both MaxHealth and HealthType.