The phrase "our twelve tribes" stands for the people in those tribes. Alternate translation: "this is what our fellow Jews in the twelve tribes sought to receive" (See: [[rc://en/ta/man/translate/figs-metonymy]])
This speaks about a promise as if it were an object that can be received. Alternate translation: "the promise ... were waiting for God to fulfill" (See: [[rc://en/ta/man/translate/figs-metaphor]])