Learn English – I should have done this. VS I should have been to do this

This is called backshifting. When we use indirect speech, we often put the contents of the speech further in the past.

Let's first take a direct speech sentence:

Lekon Chekon said: "People who were brave enough to fight in WW2 should serve as examples to us".

Now let's report what Lekon Chekon said, and backshift the tenses he used:

Lekon Chekon said that people who had been brave enough to fight in WW2 should serve as examples to us.

This sentence employs indirect speech (no quotation marks). We backshifted were to had been.

Thus, your first sentence is correct. Note that even in the direct speech sentence we can use have been only if Lekon Chekon's words were pronounced during WW2:

In 2015, Lekon Chekon said: "People who have been brave enough to fight in WW2 should serve as examples to us". (WRONG: WW2 ended a long time ago)

In 1942, Lekon Chekon said: "People who have been brave enough to fight in WW2 should serve as examples to us". (RIGHT: WW2 is still going on)

While the above answers do make sense they come off as blaming the other person.
I would instead try something like

I think there has been some miscommunication.

This way no one is being blamed but the issue is still raised.