I don’t think it is necessarily good or bad for epilepsy. Having a teaspoon of apple cider vinegar a day can actually beneficial for health and multiple parts of the body, helps with cleansing it out and strengthening your immune system.

i'm a hippie guy (alternative meds). i there is nothing about vingar causeing seizures. i sometimes take apple cider vinegar or wine vinegar or white vineger or rice vineger... and i have immune system seizures (food seizures). the only benefits to vineger is apple cider vineger. the benefits are blood sugar, digestive health, lose weight, antimicrobial properties, and heart health. the only thing that is bad is if you are doing it on a daily basis. apple cider vineger is acidic so too much of it will make you burn, irritation, and discomfort. and if you have stomach ulcers... it will be 10 times worst.
my advice is do apple cider vineger 1-3 times a week (depending on your size and weight).