Right, these men sent from James were not the same men who came from the Pharisees. The Jewish Christians practiced some of the external adornments of the Law, and some of them may still have thought they had to observe things like Sabbath and circumcision. But James did not ultimately advocate for these things because he recognized, along with Paul, that they were no longer under the Law.
Being Jews, however, they were accustomed to practicing traditions which, if they wanted to maintain civility among the Jews, felt it wise to maintain some Jewish traditions. That is clearly how Paul himself described it. And he and James were in perfect agreement about that.
The men who came from the Pharisees, again, were *not* the same men who came from James. The men who came from the Pharisees were *not* genuine Christians, and were committed to practicing the Law in full. You are conflating the two groups.
Here is the 1st group, which was *not* affiliated with, nor associated with, the group who mentioned in Gal 2.12 who came from James:
Gal 2.4 This matter arose because some false believers had infiltrated our ranks to spy on the freedom we have in Christ Jesus and to make us slaves. 5 We did not give in to them for a moment, so that the truth of the gospel might be preserved for you.
This is the 2nd group, which *was* affiliated with James:
Gal 2. 9 James, Cephas and John, those esteemed as pillars, gave me and Barnabas the right hand of fellowship when they recognized the grace given to me. They agreed that we should go to the Gentiles, and they to the circumcised. 10 All they asked was that we should continue to remember the poor, the very thing I had been eager to do all along.
11 When Cephas came to Antioch, I opposed him to his face, because he stood condemned. 12 For before certain men came from James, he used to eat with the Gentiles. But when they arrived, he began to draw back and separate himself from the Gentiles because he was afraid of those who belonged to the circumcision group.