At present WHMCS can check availability for IDNs on standard TLDs such as ,com, .net and .org.
Please add the ability to also check the availability of Internationalized country code top-level domains, such as:
.中国 (encoded as ".xn--fiqs8s") and .中國 (encoded as ".xn--fiqz9s"; ".zhongguo")
.香港 (encoded as ".xn--j6w193g"; ".hongkong")
.台灣 (encoded as ".xn--kpry57d") and .台湾 (encoded as ".xn--kprw13d"; ".taiwan")
More information is publoished here: https://en.wikipedia.org/wiki/Internationalized_country_code_top-level_domain
I'm pleased to announce that in v8.0 we have improved International Domain Name support. Enom and ResellerClub support automatic IDN registration, and you'll benefit from robust IDN validation and usability improvements.
Please test it out, and let us know your feedback during the pre-release period.
Beta information: https://beta.whmcs.com
Feature Documentation: https://docs.whmcs.com/International_Domain_Names
Feature spotlight: https://blog.whmcs.com/133640/improved-idn-support-in-whmcs-80
Community Discussion: https://whmcs.community/topic/301978-improved-idn-support-share-your-experience/