Wsa distinguishes between musical "affinity" and "ability". What do you have to say about sudden, drastic, accelerated emergence of [all] abilities?

Like vs can do. I am not aware of these as technical medical terms. Affinity generally means drawn to, to want to be a part of, feeling at ease with something. Ability means the potential to learn a skill or to possess a skill. People can have affinity to music but not be able to learn to play music. Cases of sudden emergence without practice usually to brain processes causing a change in structure or function.