Epilepsy is a clinical diagnosis, not an EEG diagnosis. Certain EEG abnormalities are closely associated with epilepsy, but do not make the diagnosis. Conversely, a normal EEG does not guarantee that someone will not suffer from epilepsy (hence the removal of the requirement for the huge number of normal EEGs carried out).
All the CAA can do is weigh up the available information to come up with a calculation of risk. The acceptable risk depends on what type of licince you hold, and what type of operations you intend to carry out.