(I’m not a doctor, I just study medicine in my spare time)

As far as I can research, a seizure from hypoglycemia is called a "secondary seizure" and isn’t the same as true epilepsy. It might happen again if the hypoglycemia happens again, but as long as her blood sugar stays good, then more seizures shouldn’t just spontaneously happen.

If she didn’t really need a stress dose, I’m not sure what would cause it. Some people are just naturally prone to hypoglycemia, I see papers where they say it’s caused by not enough (sweet) food and/or too much activity, or too much excitment. I saw one paper that said it can be a prelude to type-1 diabetes. Hopefully she doesn’t have that.

I don’t know if an (unnecessary?) stress dose would instantly stop the hypoglycemia. That might be a good question for an endo.