From what I hear, we learn more about what Ishy has been up to in regards to Rand in ToM. It sounds like he has not been quite as much of a failure as it looks like so far. And even if he has, it clearly hasn't been of the magnitude of mogy or graendal.

And I wouldn't call Semi a failure. She likely would have been absolutely successful against Rand not once, but twice, if not for two things she had no way of knowing about. First Cads' ter'angreal, which noone had any way of knowing about, is what messed her up the first time, and Rand's access to the TP is the only thing that saved him the second. But she didn't get punished by the DO, so I don't really see how this is relevent.

But I think that the female forsaken have, as a whole, created worse disasters for the Shadow than the male forsaken, so of course they have been punished more. You can say that the fact that RJ set up the female forsaken to be even more incompetent than the male is a sign of sexism if you want...I personally think it was just a plot necessity, since the female forsaken have more frequently faced people other than rand, who are not as badass as him, and so need to be more pathetic to still lose.