Hard Beatrix is mechanically separate from Normal Beatrix, with different base stats and different attacks. You even get a new Bestiary entry!
The Antifairies won't appear in the Hard Challenge. They're holding off for something else, much later. (There is, however, a Hard Tower Lord who's more or less from the same general neighborhood.)
I'll give Petty Fiends/Bitter Jab a look later. The general area is getting attention fairly soon, after all.