I’m still translating Agapius. In part 1.1, while discussing the length of the lives of the Patriarchs, he performs a calculation based on the Septuagint. He then gives the values from the Jewish Torah, commenting on how the Jews changed the text after Christianity came long. He then says:
The Syriac Torah depends on the Torah (of the Jews), because it was translated from Hebrew after Christianity and the deterioration (of the text).
I’m not sure whether modern scholars are certain of when the Old Testament was translated into Syriac, which makes this testimony interesting.