https://eventespresso.com/topic/replace-text-on-event-page-script-not-working/

strings.php

<?php
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file

function tw_custom_filter_gettext( $translated, $original, $domain ) {
 
    // This is an array of original strings
    // and what they should be replaced with
    $strings = array(
        'Sold Out' => 'Class Full',
        // Add some more strings here
    );
 
    // See if the current string is in the $strings array
    // If so, replace its translation
    if ( isset( $strings[$original] ) ) {
        // This accomplishes the same thing as __()
        // but without running it through the filter again
        $translations = get_translations_for_domain( $domain );
        $translated = $translations->translate( $strings[$original] );
    }
 
    return $translated;
}
 
add_filter( 'gettext', 'tw_custom_filter_gettext', 10, 3 );

function add_cap_to_access_message( 
    $text, 
    $ticket, 
    $ticket_price, 
    $ticket_status 
) {
    
    $cap_required = '';
    $cap_required = $ticket->get_extra_meta('ee_ticket_cap_required', true);
    $search = '_';
    $replace = ' ';
    $cap_required_display_name = str_replace( $search, $replace, $cap_required);
    $text =  'This course is restricted to ' . $cap_required_display_name . ' employees.';
    return $text;
}

add_filter(
    'FHEE__EED_WP_Users_Ticket_Selector__maybe_restrict_ticket_option_by_cap__no_access_msg', 
    'add_cap_to_access_message', 
    10, 
    4
);