Help please

Hi,
Plugin is perfectly working for Arabic characters with WP.
I’m using a theme that has a Register Form, and it’s not Accepting Arabic,
i searched Register template and found this code:

* validate user name
*/
if( !$data[‘user_login’] || !preg_match(‘/^[a-z\d_]{2,20}$/i’, $data[‘user_login’]) ) {
return new WP_Error( ‘username_invalid’, __(“Username only lowercase letters (a-z) and numbers are allowed.”, ET_DOMAIN) );
}

And another file (class authentication) is using this code:

if (!preg_match(“/^[a-zA-Z0-9_]+$/”, $userdata[‘user_login’])) {
return new WP_Error(‘username_invalid’, __(‘Username is invalid’, ET_DOMAIN));
}

I appreciate your help.
Thank you.

https://ww.wp.xz.cn/plugins/wordpress-special-characters-in-usernames/