For most of the history of European learning the Samaritan Pentateuch was known about and not known. Christian writers of late antiquity mention it, so the fact that a separate Torah in a separate script existed was never entirely lost, but no copy was available in Europe and nobody could check what it said.
That changed in the seventeenth century. A manuscript of the Samaritan Pentateuch was acquired in the Levant by the Italian traveller Pietro della Valle in 1616 and brought to Europe, and its text was printed in the Paris Polyglot Bible, the great multilingual edition that set the Hebrew, Greek, Latin, Syriac, Arabic and Samaritan texts of scripture in parallel columns, and afterwards in the London Polyglot. For the first time scholars who would never meet a Samaritan could compare the two Torahs line by line.
The argument that followed was immediate and long. Where the two texts differ, which stands closer to the original, and what does the answer imply about the transmission of the Torah as a whole? Positions hardened along confessional lines before the evidence was in, and the question was reopened in the twentieth century when the Dead Sea Scrolls produced manuscripts older than either tradition, some of which agree with Samaritan readings.
The community itself was not a party to any of this. It was being read about rather than consulted, which is one reason the modern scholarly literature makes a point of the difference between studying the Samaritan text and knowing the Samaritan people.