[Act 15:12-19 CSB] (12) The whole assembly became silent and listened to Barnabas and Paul describe all the signs and wonders God had done through them among the Gentiles. (13) After they stopped speaking, James responded: "Brothers and sisters, listen to me. (14) "Simeon has reported how God first intervened to take from the Gentiles a people for his name. (15) "And the words of the prophets agree with this, as it is written: (16) "After these things I will return and rebuild David's fallen tent. I will rebuild its ruins and set it up again, (17) "so the rest of humanity may seek the Lord -- even all the Gentiles who are called by my name -- declares the Lord who makes these things (18) "known from long ago. (19) "Therefore, in my judgment, we should not cause difficulties for those among the Gentiles who turn to God,
I think verse 17 should be amended to:
so the remnant of men may seek the Lord -- even all the men of the nations who are called by my name -- declares the Lord who brings these things about
This connects with Isaiah:
[Isa 10:21 NASB] (21) A remnant will return, the remnant of Jacob, to the mighty God.
[Isa 28:5 NASB] (5) In that day the LORD of hosts will become a beautiful crown And a glorious diadem to the remnant of His people;
[Isa 46:3 NASB] (3) "Listen to Me, O house of Jacob, And all the remnant of the house of Israel, You who have been borne by Me from birth And have been carried from the womb
So if this is correct it seems to not be about the gentiles but rather the diaspora, scattered among the nations.
So why does James conclude from this passage that the gentiles were welcome and did not have to get circumcised or observe Jewish orthopraxy? It doesn't seem to follow.