I don’t put a lot of stock in him either (though I think his ecclesiology is one of his strong points). But he’s certainly a mainstream Protestant figure, and a claim about historic Protestantism that is false of Calvin is a rather dubious claim.
Which sins and errors do you mean then?
The usual litany–persecution of heretics, restriction of lay access to Scripture, adoption of many of the methods of the Roman Empire, failure to recognize the positive aspects of the Protestant Reformers’ ideas. . . .
First of all, it’s my understanding that the Church has apologized for many of these.
The Pope apologized/repented, yes, and I admire him for doing so. But he made a point of repenting for actions by members of the Church, avoiding the phrase "the Church has done . . . " Ecclesiologically, he had to speak this way. I don’t fault him personally. But I do see it as an example of the Catholic acceptance of an “invisible Church.”
Second, no one said the visible Church would be perfect. It is guided into truth, but not perfect.
Well, check this with knowledgeable Catholics. But my understanding is that Catholics do say, when speaking strictly and simply, that the Church is perfect and sinless. That indicates that the primary sense of the Church for you is not what most of us mean by the “visible Church.”