And yet you are still unable to provide the actual source from Ibn Kaspi's writings. Why is that so?
Rashi changed the position that the Suffering Servant was the Messiah to refute the belief that Jesus is the Suffering Servant. The Suffering Servant of Isaiah – A Rabbinic Anthology | Jewish Awareness Ministries
The Suffering Servant in Rabbinic Controversy
Judaism solidly taught that the Suffering Servant was the Messiah until a very influential Talmudic commentator Rabbi Shlomo Itzchaki, 1040-1105 CE (called Rashi) and some of the later rabbis began to interpret the passage as referring to Israel. In Rashi’s own words this was a defensive move to take away the case made by Christians that the Suffering Servant was fulfilled in Jesus.