I suspect that Cardinal Ratzinger was thinking of something like this when he told a reporter that there is plain evidence that the Holy Spirit does not always make the choice of a pontiff. The dispositive evidence? There were more than a few, he noted tartly, that he would be quite reluctant to blame on the free choice of the Holy Spirit. In fact, he couldn't even imagine the Holy Spirit picking some historical popes he could think of.
But the good cardinal, as learned as anyone in the riches of the Catholic theological tradition, did allow as how he very much counted on the Holy Spirit to protect the Church, so that no matter what, nothing completely damaging would happen. We have the promise of that: The Holy Spirit will protect the Church, though fierce storms rage, until the end of time.
And so, when Catholics speak of the "Holy Spirit" playing a role in the conclave, don't try to imagine a puppeteer pulling strings. The better image is that of the novelist, creating free, living, breathing, conflicted characters who make choices, and in doing so tell with these choices a magnificent story of liberty. The novelist who plays puppeteer convinces few readers that his characters are real. Real artistry lies in creating characters who are free, and who act from within the depths of their own liberty. So it is with the Artistry of the Holy Spirit in the theater of the conclaves down the centuries — a free God, Who chooses to be honored by the flawed efforts of free humans to respond to Him in their own liberty.