I am sorry for what you and Jake are going through. It is frustrating to go through vets, specialists and not getting a proper diagnosis. Unfortunately, seizures, especially with aging dog may have many different origins.
One possibility is Jakeís seizures are related to his decreasing renal function. It is not uncommon myoclonic seizures (I think this is what I see in the video, uncontrolled muscle movement and twitching) accompany the progression of kidney disease.
You say Jake had his full blood work and it was OK. Do you do urine tests to assess the progression of his renal disease? Does he have proteinuria, what is his urine concentration? The blood parameters can be perfectly normal until about 85% of kidneys function are compromised. My dog had perfect blood readings the same week he passed away from kidney failure, but he had severe proteinuria and his urine concentration was 0 for a few months before he died. For us the first sign of the problem was also his hind legs giving away. There are many reasons for this, but one of them is the renal failure.
Gabapentin can worsen myoclonic seizures. See the link to the epilepsy journal. With renal disease and seizures, the recommend medications are from benzodiazepines family. Treating seizures in renal and hepatic failure
Keeping Jake on enalapril is a good thing. Do you measure his blood pressure; maybe he needs a higher dose of enalapril. In addition, you mention Jake is on home cooked diet (my dogs as well). You want to feed him high quality, low protein diet (egg whites, fish etc) avoiding too much phosphorus.
I also recommend CBD oil. I currently have a dog with some sort of neurological movement issue. It might be seizures, though if they are they are very different from the typical ones. I think he has paroxysmal dyskinesia so the AED drugs donít work anyway. My guy was on gabapentin for a bit but it didnít work.
Good luck to you and Jake! Please keep us posted. I hope for no more seizures.