Q:

Preposition to use with the phrase "come to an understanding"

So, I'm to translate a sentence to English. It's something like:

We've succeeded in coming to an understanding ______ all questions discussed. 

I suppose that I should use either about or in to fill the blank in the sentence above. Here is a paraphrased sentence so that you're able to understand the meaning better: 

We've discussed several questions and we've come to the same opinion on every one of them. 

(Aside: I wonder if I used the correct preposition in the sentence above.) 

A:

We've succeeded in coming to an understanding on each of the
  questions discussed.

This implies that if each question were enumerated, agreement would be note for each and every one.
But "succeeded" and "discussed" are arguably redundant. This is equivalent:

We've come to an understanding on each of the questions.

