SH very explicitly told Semirhage that it was her last chance. Based on that, I think she obtained SH's instructions to the letter. I don't think she waivered much from SH's plan. I personally feel that SH wanted Semirhage to force Rand to torture Min.

The biggest hint that you did not mention was that the Choedan Kal was left behind. This, IMHO, clearly indicates that SH never intended for Rand to go to Shayol Ghul. I think they did whatever they could to get Rand to draw the True Power on purpose. Rand may have even had the thought of the True Power in the first place because Moridin actively lent him that thought.

I think the true purpose of this attack was to get Rand to go crazy and then draw then True Power. They then left the Choedan Kal behind as way for him to inflict his dark craziness as maximally as possible.

I think this attack was very well thought out. I think they used Semirhage as the sacrificial lamb to turn Rand to the dark. The plan worked beautifully, if that indeed was the plan.

By the way, I have read this section 4 times now and I don't see any indication that the True Power was supposed to be as powerful as the one power with the Choedan Kal. I think the intent of that passage was to show how much power Rand felt--- it had more to do with the drug-like addictive nature of the true-power than the actual power of the true power. Just like a drug, Rand perceived that he was all-powerful with the True Power--- but that is no different than someone on LSD thinking they can fly.