Joey's had a Protein C test already, right? That's the next step after two high bile acids. If indicated, the next step would be scintigraphy. Don't waste your money on an ultrasound even though many vets who aren't up to date on the current protocol will recommend them. The results are only reliable about 80% of the time according to Dr. Center, as low as 60% according to Dr. Tobias, I believe.
It's possible you may be dealing with idiopathic epilepsy completely separate from his liver issues. Lady has epilepsy along with a laundry list of other health issues. Idiopathic epilepsy is organic epilepsy meaning there is no known reason for the seizures. They are not a symptom of another disease. That type of epilepsy most commonly starts between 1-5 years of age. My Lady was four when she started having seizures.
Has your vet done a thyroid panel? A thyroid imbalance can also cause seizures. Lady is hypothyroid in addition to her epilepsy - her seizures are not a result.
Yup, she's a mess, but I love her.

She's a rescue and poorly bred, so her genetic time bombs started going off when she was Joey's age.
The key when you have a dog who may have a several different health issues going on at the same time is to have a really good vet....and a big bank account.