Example of changing 'Upcoming' to 'Registration Open'.

ee_tw_localized_status__translation_array.php

add_filter('FHEE__EEM_Status__localized_status__translation_array', 'ee_tw_localized_status__translation_array');
function ee_tw_localized_status__translation_array( $translation_array ) {
    //Upcoming
    $translation_array[EE_Datetime::upcoming] = array(
        'registration open', //singular
        'registration open', //plural
    );

    // You need to return the localized statuses to the filter.
    return $translation_array;
}