I'm not familiar with epilepsy meds, but there are meds that dehydrate and/or are known to cause kidney stones.
Ketosis itself is not related to stones at all.
And as long as you have healthy functional kidneys and don't have a history of stones(and are not on meds that put you at high risk) oxalates in foods are not an issue.
I have brain issues as well, though not epilepsy, and I have to take two meds for it that are know causers of CalOx stones, and one is specifically to cause my body to be unable to retain water because of elevated brain pressure (it dehydrates me)... that said my doctors are also very positive about me staying Keto as a part of my treatment.
Staying HFLC has allowed me to cut the amount of meds I take drastically. Seriously drastically... from 3kmg/day to only 500-1kmg day! So... yeah. Keto it is.
There are some steps that I take to try and prevent crystals from building up in my kidneys so that I hopefully never have a stone event... so far it has worked.
I avoid foods in the Very High and High oxalate range most of the time. I drink copious amounts of water to keep my kidneys flushed and clean, and I dose all my water with lime, key lime, or calamondin juice (simply because I prefer those to the taste of lemon) in order to keep the acidity of my urine a little high to erode any crystals that might form. And I supplement some potassium citrate.
This has evidently worked. I get my urine tested regularly at Neurologist appointments and I'm always clear... my doc's are happy but have expressed their surprise, especially during the time I was at an extremely high dose of my meds when I was doing higher carb Paleo.