I'm a little slow, but...

So I was reading this story recently about how Lutherans, Catholics, and Methodists signed a historic document, jointly agreeing on the doctrine of justification. Actually, the Catholics and Lutherans apparently signed it a few years ago, with the text here.

Now I'm a bit slow when it comes to doctrinal stuff, but a few questions sprang to mind reading through the document.

What has changed in the past 400 years? Is theology progressive, like science? Are we better at philosophy, theology, and ethics than we were 400 years ago? Are we smarter than the men (both sides) debating then? I'm not at all convinced that theology is like technology, which gets better with every generation.

The declaration has statements like

Our common way of listening to the word of God in Scripture has led to such new insights.

and

The Lutheran churches and the Roman Catholic Church have together listened to the good news proclaimed in Holy Scripture. This common listening, together with the theological conversations of recent years, has led to a shared understanding of justification.

What about each groups' understanding has changed? It's great that new insights and a shared understanding have been reached. What were they reach from? Whose understandings have changed in the last 400 years?

Out of curiosity, how did this issue get so misunderstood 400 years ago that doctrinal condemnations were issued? Is anyone the least bit apologetic for false condemning the other falsely? (Were those condemnations false?)

Could a document this important be written in a way that a common American could understand? I'm all for incomprehensible theology, but it'd be nice to have a "what we really mean is ..." version.

Could one finish the must statements with consequences?

But the justified must all through life constantly look to God's unconditional justifying grace [or else what?]

The justified also must ask God daily for forgiveness as in the Lord's Prayer (Mt. 6:12; 1 Jn 1:9), are ever again called to conversion and penance, and are ever again granted forgiveness. [Or else what?]

Is this Johnny must eat his peas or else he won't have desert? Johnny must eat his peas or else he will be spanked? Johnny must eat his peas or else he will be shipped to outer Mongolia?

The justified must ask God daily for forgiveness or else what...? They aren't forgiven for their sins? They suffer disconnection from God despite remaining his children? God smites them with lightning?