I’m sorry about the essential tremor. I have no idea whether keto will help or not. I suppose it depends on what causes the tremor, and if any damage is reparable or not.
With all these neurological conditions, the problem is insulin-resistance in the brain, and damage to cells from lack of energy. The brain requires insulin to metabolise glucose, but ketones enter brain cells by a different receptor, so ketone metabolism often works just fine, even when glucose metabolism in the brain does not.
But past a certain point, of course, there has just been too much damage for the brain to heal, and perhaps the best that can be expected is to halt the deterioration. I just posted (in the Resources forum) a lecture by a neurologist who put an Alzheimer’s disease patient on a ketogenic diet. While his motor skills and cognition did not improve, they didn’t deteriorate, either, which is contrary to expectations for the disease. And his quality of life score improved significantly.
My guess is that the brain might possibly heal from some damage, but we know that neurons regenerate very slowly, so that any healing might not be noticeable, especially in the short-term.