Nope. “Grafted on” does not make them accountable to the Judaic law.
Your post here is an empty claim (strawman) that no one is talking about and does not address the content you are responding to.
As posted earlier, according to the scriptures both ISRAEL and a JEW in the new testament are all those who believe and follow God's Word. Gentile believers are now grafted in to God's ISRAEL *
ROMANS 11:13-27.
ROMANS 9:6-8 [6], FOR THEY ARE NOT ALL ISRAEL WHICH ARE OF ISRAEL,: [7], NEITHER, BECAUSE THEY ARE THE SEED OF ABRAHAM, ARE THEY ALL CHILDREN: but in Isaac shall thy seed be called <Christ> [8], That is, THEY WHICH ARE THE CHILDREN OF THE FLESH, THESE ARE NOT THE CHILDREN OF GOD: BUT THE CHILDREN OF THE PROMISE <those who believe> ARE COUNTED FOR THE SEED.
God's ISRAEL are all those in CHRIST that have been given a NEW HEART according to the NEW COVENANT promise...
ROMANS 2:28-29 [28], FOR HE IS NOT A JEW WHICH IS ONE OUTWARDLY; NEITHER IS THAT CIRCUMCISION, WHICH IS OUTWARDS IN THE FLESH: [29], BUT HE IS A JEW WHICH IS ONE INWARDLY; and CIRCUMCISION IS OF THE HEART, IN THE SPIRIT, AND NOT IN THE LETTER; whose praise is not of men, but of God.
As posted earlier through the new covenant scriptures, Gentile believers are now grafted in to God's ISRAEAL. If you are not a part of God's ISRAEAL accoding to the new covenant promise given in JEREMIAH 31:31-34 and repeated in the new covenant scriptures in HEBREWS 8:10-12 you have no part in the new covenant. Being a part of and grafted in to God's ISRAEAL makes gentile believers no longer gentiles but a part of God's ISRAEAL defined in the scriptures as all those who believe and follow Gods' Word and bound by faith to believe and follow what God says.
Hope this helps