The above reply of mine is correct. So I was going through some articles and in this article, it is mentioned that https://wpml.org/forums/topic/cannot-translate-error-the-username-or-password-you-entered-is-incorrect/
this is happening due to the Wordfence plugin.
when the Wordfence plugin is activated, its own message overwrites the default WP message, therefore, causing it to not be translatable.
Due to which the string is still showing in English, even the site language is different
Either deactivate that plugin or you can try this code in wplms customizer plugin
add_filter('login_errors','login_error_message');
function login_error_message($error){
//check if that's the error you are looking for
$pos = strpos($error, 'incorrect');
if (is_int($pos)) {
//its the right error so you can overwrite it
$error = "Heyyyaaa. <a href='your-site-url/wp-login.php?action=lostpassword'>Lost Password?</a>";
}
return $error;
}
Or you can check these: https://www.wpbeginner.com/wp-tutorials/how-to-disable-login-hints-in-wordpress-login-error-messages/