Using an IDN internationalized domain name in Thai appears to work fine. However when using WP Multisite Subdomain network and trying to ADD SITE as a SUBDOMAIN - it is not accepting the Thai characters and generates error "Missing or invalid site address."
I tried changing some setting in phpMyAdmin collation and wp-config.php but didn't really know what to do with that, and plugin intlWP which looked like it would do it, has not fixed the problem of using Thai as the subdomain site address.
this isn't a translation issue, it's a URL and WP Admin interface issue I think.
there has to be a way to have a WP multisite using Thai language subdomains... any suggestions welcome. thanks