Most of the NT quotes found in the NT are taken from the Septuagint, which uses the word Greek "kyrios" to translate "YHWH". In Malachi 3:1, God said that He would send a messenger that would prepare a way before Him, and in Isaiah 40:3, it says to prepare the way for kyrios or YHWH. In Mark 1:2-3, it quotes this passage in regard to preparing the way for Yeshua, so he was saying that Yeshua was the kyrios or YHWH. Again, in Mark 2:28, Jesus said that he was the kyrios of the Sabbath, so he was clearly identifying as YHWH, who gave the Sabbath regulations. In Psalms 89:8-9 and Psalms 107:23-30, it is YHWH who has command over the sea and the wind and who calms them, and in Mark 4:39-41, it is Yeshua who commands what only YHWH has command over. Furthermore, in Mark 6:48-51, Jesus walked in the water, and in Job 9:8, it is God alone who stretches out the heavens and treads on the waves of the sea. His response of "I AM" in verse 50 is also a claim to being God, who controls all of nature. In Psalms 103:2-5 and many other verses, it is YHWH alone who forgives sin and heals all of our diseases and in Mark 2:5-12, that is what Yeshua did. In 1 Samuel 8:6-7, it is YHWH who is King of the Jews, so Yeshua was identify as YHWH when he said that he was King of the Jews in Mark 15:2. There are many other verses that proclaim YHWH is King and Yeshua is our only King.
Yeshua is also addressed many times as kyrios throughout Matthew, and considering that it was written to a community of Jewish believers, they would not have missed that connection. Again, he referred to himself as kyrios in Matthew 7:21-22. There are many verses in the OT where it is YHWH who judges, yet here it is Yeshua who is judging on the last day. In Matthew 25:31-46, it again Yeshua who is judging and the Son of Man who is kyrios. Only YHWH was worshiped by Jews, but Yeshua was worshiped in Matthew 2:2, 2:11, 14:33, 28:9, and 28:16. There is more, but I think this should be sufficient to show that the writers of the Gospels considered Yeshua to be YHWH.
There is a difference between adding a new command and explaining what is there. In Nehemiah 8:8, it says that they read from the Book of the Law of God, making it clear and giving the meaning so that the people understood what was being read, and it does not treat it like they were committing a sin. Where the Targum has value in not in being a literal translation, but in expressing how these concepts were anciently understood.
The New Covenant is Israel's remarriage to Yeshua and Romans 7:4 is speaking in this regard about Israel's remarriage to Yeshua and about how his death was what allowed this to happen in accordance with the Law.