This function can be used to translate all of the text strings within the default ticket template. Add the function to your themes functions.php file or add it within a site specific plugin. Each line is currently commented out, remove the // from the begging and add your custom text within the right side within ''

functions.php

<?php
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file
function ticketstrings_filter_gettext( $translated, $original, $domain ) {
 
    // This is an array of original strings
    // and what they should be replaced with
    $strings = array(
        'Ticket for' => 'Custom Text',
        //'Print Ticket' => '',
        //'Download PDF' => '',
        //'Print and bring this ticket with you to the event' => '',
        //'ID:' => '',
        //'Qty.' => '',
        //'Location: => '',
        //'More Information:' => '',
        //'Ticket Instructions:' => '',
        //'Powered by the <a href="%s" target="_blank">Event Espresso Ticketing System</a> for WordPress' => '',
        // 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', 'ticketstrings_filter_gettext', 10, 3 );