The Bible defines its own terms.
Romans 11:25 “For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fullness of the Gentiles be come in.”
God wrote the phrase: “fullness of the Nations be come in”
This is an old testament quote for Ephraim.
Genesis 48:19 “And his father refused and said, I know, my son, I know. He also shall be a people, and he shall become great. But his younger brother shall become greater than he, and his seed shall become the fullness of the nations.”
The bible at times uses the name Ephraim to mean those of the divorced Ten Northern Tribes who were living in Europe at the time of Christ. They were reunited with Israel under one head, Christ, as promised in Hosea 1:10-11 and is shown in Ephesians 2:11-22.
There is no need for a Plan B or Spiritual Israel. Christ did not fail. True Israel is mostly Christian today.
The modern day Jews are not God’s Israel people. They do not fulfill over 100 bible promises.