Hello,
This is a known issue, case #CORE-8560, where whenever someone look up a domain with non latin characters, the results appear in IDNA encoding. All registrars from countries with non latin characters, we cannot upgrade to v.6 until v6 reverts to the way IDNs were displayed in WHMCS 5, i.e. in utf-8 encoding.
Please give some priority to case #CORE-8560, we cannot upgrade until this is fixed.
Thanks in advance.