Translators may insert a paragraph break here, as in Good News Bible.

When the terms had been fully considered may be rendered “After they all had decided the details of the peace treaty.”

And the leader had informed the people, and it appeared that they were of one mind, they agreed to the covenant: It is not clear who the leader and the people are. However, we believe that Good News Bible is wrong in identifying the leader as Nicanor. We believe it is Judas (see verse 16, where the same phrase is applied to Judas). Nicanor’s representatives took the initiative by coming to the Jews. Whoever was involved in the discussion, both sides agreed that a treaty (covenant) was in everyone’s best interest. The Syrian delegation would have to return to Nicanor’s camp to get approval, but Nicanor, the Syrian general, was not going to take a vote of his troops to decide action. However, Judas had to be sure that he did not take any action in which the Jewish patriots fighting with him would not support him. So the leader refers to Judas and the people refers to his army. Judas went to his army to discuss the potential treaty and ask for their approval. They agreed to the covenant does not mean they agreed to a treaty already made. They agreed it should be made. The actual treaty was made by Nicanor and Judas themselves in verses 21-22. Here in verse 20 there was only a preliminary discussion. It was only after this discussion that the Greek delegation returned to Nicanor to inform him that the Jews agreed to discuss peace.

Here is an alternative model for this verse:

• There was a long discussion of possible peace terms [or, They all discussed the details of a peace treaty], and then Judas informed his men. They all agreed that such an arrangement would be good.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on 1-2 Maccabees. (UBS Helps for Translators). New York: UBS, 2011. For this and other handbooks for translators see here.