Very unlikely that the hi will return.
Black can come back but it is rare for red. There were some articles in KOI USA several years ago from Joel Burkhard that had Kohukus that "grew" hi. I bought a Sakaguchi (sp) showa this spring and the same has happened on the first patch-it's mostly disappeared. I'm not sure I'll buy that breeder again. I plan to auction my fish when I get a chance. Sorry to hear-that's what makes this hobby difficult.