They do not appear to have existed
I remember looking for this one back when the linked question was posted and finding nothing and looking again today I found nothing indicating there has ever been a Pakistani Batman.
To start the DC Database page on Black Bat mentions only the following characters:
Considering the below description it is entirely possible that the Wikipedia editor misinterpreted Cassandra to be Pakistani or just assumed it and she is also the most likely candidate it is referring to.
Cassandra was the first Batgirl to star in her own ongoing Batgirl comic book series, an Asian character who was replaced as Batgirl by Stephanie Brown in a 2009 storyline. She returned in late 2010, where she was shown working as an anonymous agent of Batman in Hong Kong before adopting the new moniker of Black Bat.
Wikipedia, Cassandra Cain
Another character named "Black Bat" but she is not Pakistani or even Asian.
Barbara Gordon Hardy was an ex-thief who was determined to become a S.H.I.E.L.D. agent. Using her natural athletic skills to fight crime, she created a superheroic identity, the Black Bat. She quickly proved her worth to S.H.I.E.L.D. agent Bruce Wayne. Barbara was invited to join the secret organization.
Sam is only mentioned to have used this alias during the American Civil War and so unlikely to be a candidate for a Pakistani Batman but no citation is given.
Looking a bit further we can see Black Bat was only added to Wikipedia on 17 August 2018 by an anonymous user, see the revision here. Therefore, as it is uncited it could be this user was trolling/vandalising the page, has some obscure knowledge that "only they" know or are just misguided and got confused. Either way as they provide no citation/source it is more likely to be false.
And on a side note maybe the editor assumed this was real: What if your favourite superheroes were Pakistani? Find out here.