Update library/Zend/InputFilter/BaseInputFilter.php

I think an access to that list is necessary, for eg if you want to 
retrieve the full list and apply to all validators a translator instance

foreach($inputFilter->getInputs() as $input)
foreach($input->getValidatorChain()->getValidators() as $validator)
$validator->setTranslator()

I know there is AbstractValidator::setDefaultTranslator(); for example above