A bit OT, but what the heck...
The events are just a fancy name for "hooks" really. It simply allows you to inject code into certain points in the bootstrap process. You could of course also use this same functionality within your application to make it easily extendable.
A type validator (assuming your talking about the opt component) can be any function that returns a bool. To use your example:
$ops = $this->setOptions([
'user_email' => (new Option())
->addTypeValidator('email', function($value) {
return filter_var($value, FILTER_VALIDATE_EMAIL));
})->type('email')
], $options);