The error produced here tells something else and contradictory to the content written by ICANN on whois page.

It seems that this ICANN Whois is valid only for gTLDs not for all other domains. I tried buy.ooo , it gives me result for .ooo but it shows error if i try datamail.in (as its ccTLD)

Maybe it’s very specific then. I used डाटामेल.भारतand xn--c2bd4bq1db8d.xn--h2brj9c. Whois.com finds both. Whois.icann.org serves

From: Marc Blanchet [mailto:marc.blanchet@viagenie.ca]
Sent: Thursday, June 28, 2018 18:35
To: Mark Svancarek <marksv@microsoft.com>
Cc: ua-discuss@icann.org
Subject: Re: [UA-discuss] How do I log a bug related to ICANN WhoIs portal?

works for me with either A-Label or U-Label. Marc.

On 29 Jun 2018, at 8:30, Mark Svancarek via UA-discuss wrote:

https://whois.icann.org/en does not successfully locate IDN domains even if the domain name is input as ALabels.