A good archaeological, linguistic, cultural, and geographical study on this subject is written by Yair Davidy. Yair is a Jewish scholar based out of Jerusalem. He along with thousands of Orthodox Jews agree that the lost tribes were scattered but will be regathered by the soon coming Messiah.
By the way, the editors of THINGS TO COME (1894 to 1915) also believed that the tribes were scattered just as you state. They were Bible-literalists.
The word “scatter,” however, is not synonymous with the word “lost.” All Twelve Tribes were represented at Pentecost in Acts chapter 2, although they had been scattered.
The volumes of THINGS TO COME dealt often with the issue of British-Israelism which was a much bigger deal in theological discussion in those years than it is today in the USA (I assume you are writing from the USA). The editors published that article in that context.
Is it possible that the entire later Kingdom of Judea was made up of the descendants of the exiles who returned in the time of Cyrus? The returning exiles just could not have been that many, especially since many exiles, perhaps the majority, didn’t return at all; the exile community in Mesopotamia kept its identity long into the Christian Era.