The question speaks for itself. i cannot find any reason why you would have a localized parameter in a custom save action. Does anyone have an example on where that is being used?
A save action item contains folowing configuration fields:
More informations you can find here: https://doc.sitecore.net/web_forms_for_marketers/working_with_actions_and_validations/the_save_action_item_fields
An example how to use it : https://doc.sitecore.net/web_forms_for_marketers/working_with_actions_and_validations/create_a_new_save_action but it's not the best example.