Translate 'Attendee %d' & 'Attendee Information' to 'Participant %d' and 'Participant Information'.

functions.php

<?php
//Please do not include the opening PHP tag.


function mycustom_filter_gettext( $translated, $original, $context, $domain ) {
 
    // This is an array of original strings
    // and what they should be replaced with
    $strings = array(
        'Attendee Information' => 'Participant Information',
	'Attendee %d' => 'Participant %d',
        // 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_with_context', 'mycustom_filter_gettext', 10, 4 );