What are some misunderstandings and myths we Catholics and others get wrong about the Protestant Reformation?
I am much better at answering what Protestants sometimes get wrong, since I know apologetics, etc.
Also because Catholics had fewer things they got wrong. . .
Kidding! Just kidding! Douse the flames. . .
On a more serious note, both sides had a very different worldview than modern people. We tend to focus on trying to bend over backward to tolerate and help each other in the ‘here-and-now’, trusting that this example will not only help get us a Utopia on earth, but also will either fit us for heaven, or ‘get us there’ (and surprisingly enough it is more the Catholic position in the first and the Protestant position in the second) even though as you note, some protestants (not all!) thought of Catholics as trying to ‘buy heaven’.
But people then focused more on the hereafter than the here-and-now. Suffering on earth for both groups was not viewed as something to be eradicated whatever the cost, but often as a necessary prelude to one’s entrance to heaven. (Note I am not saying whether this view is ‘right’ or not. I’m saying it existed to a huge extent on both sides and helps explain WHY both groups thought it not only right, and just, but also MERCIFUL to execute heretics for example). You see, IF a person were guilty of heresy, he was endangering his eternal soul. And IF a person were to suffer, even to die, that might give the person clarity into seeing where he had erred, to repent sincerely before death, and thus, even the recusant heretic or the most fiendish ‘traitor to the realm’ depending on what group you belonged to, could by that suffering cleanse himself and freely achieve the salvation which otherwise his heresy/treason would have damned him for.
Again, this type of reasoning is very hard for a person who has grown up with 400 years or so of tolerance and ‘care for the here-and-now’ behind him. Remember that in AD 1590 or so, instead of that, people had some 1500 years of 'caring for the HEREAFTER" as their sole and greatly reverenced experiences.