Can palatal myoclonus slowly improve over 5 years, no symptoms for 8 years and come back with additional symptoms? Is it normal for movement disorder

Depends. There are 2 types of Palatal Tremor ( PT). Those that are primary and called essential PT which generally does not fluctuate and tends to cause an audible click. The second form is called Symptomatic PT and may fluctuate and can have additional symptoms. This requires a neurological investigation at least once. .