I guess you could override what's being done by WPML and override home_url() the same way it does by using the hook/filter "home_url" and get the url without the lang by using $_SERVER['SERVER_NAME']; or some other way.
Maybe something like this could work :
add_filter( 'home_url', 'fix_home_url_lang', 100, 4 );
function fix_home_url_lang( $url, $path, $orig_scheme, $blog_id ) {
return 'http://' . DOMAIN_CURRENT_SITE . PATH_CURRENT_SITE . $path;
}
This doesn't take into account any multisite you could have, so be careful. Also, maybe you should use the parameters passed to the function to figure out the url you want.