Shaykh, how should we understand kashf attributed to the great imams? Since it's a personal experience, what makes it acceptable - and could anyone deemed righteous simply claim it and expect to be followed? Is it ever a hujja, or only confirmatory of the Sharia?

Kashf is not a proof in the religion, the sources are the Book and the Sunnah, so whatever is given to a righteous man is weighed against them and rejected if it opposes them. Also not every man who claimed it would have to be believed, but those that are pious like Omar Ibn Al Khattab when it happened to him on a certain occasion, then we believe in it.