Change magic login strings

change-magic-login-strings.php

<?php

add_filter( 'gettext', 'change_magic_login_strings', 10, 3 );

function change_magic_login_strings( $translated_text, $untranslated_text, $domain ) {
	if ( 'magic-login' !== $domain ) {
		return $translated_text;
	}

	if ( 'Username or Email Address' === $untranslated_text ) {
		$translated_text = 'Email Address';
	}

	if ( 'Please enter your username or email address. You will receive an email message to log in.' === $untranslated_text ) {
		$translated_text = 'Please enter your email address. You will receive an email message to log in.'; // you can update the message
	}

	return $translated_text;
}