How do I create a function that modifies a message in the wp-login.php file?

Question

When a user uses the password reset functionality in WordPress, they are asked to enter their email and click confirm. After doing so, they get the message:

Check your email for the confirmation link, then visit the login page.

I wish to modify this message, and I have found the line of code where the message is written in the wp-login.php file:

if ( 'confirm' === $_GET['checkemail'] ) {
  $errors->add(
    'confirm',
    sprintf(
      /* translators: %s: Link to the login page. */
      __( 'Check your email for the confirmation link, then visit the <a href="%s">login page</a>.' ),
      wp_login_url()
    ),
    'message'
  );
}

Changing the message there works fine and all, but am I correct in assuming that it would be overwritten as soon as WordPress is updated? If so, my questions are:

• Is it possible for me to modify this message with a function that I could put in my theme's functions.php file so that it won't be overwritten by future WP updates?

• Can I also have a translation for my new message? If I edit the translation file in the /wp-content/languages folder, I assume it would also be overwritten by an update?

Answer 1

If there is no filter to change the content, the other option is to add a function hooked to gettext - for example:

/**
 * Change text strings
 *
 * @link http://codex.wordpress.org/Plugin_API/Filter_Reference/gettext
 */
function wpse_382257_text_strings( $translated_text, $text, $domain ) {
    switch ( $translated_text ) {
        case 'Check your email for the confirmation link, then visit the login page.' :
            $translated_text = __( 'SOMETHING ELSE', 'text-domain' );
            break;
        
        case 'Another' :
            $translated_text = __( 'Whatever..', 'text-domain' );
            break;
    }
    return $translated_text;
}
add_filter( 'gettext', 'wpse_382257', 20, 3 );

ref: https://developer.wordpress.org/reference/hooks/gettext/