Gross (l.c.) thinks that Gornish may be identical with Gournay, in France, and that "M. of Gornish," apparently the author of the Tosafot of Gornish, may be Moses of Gornish and identical with the Moses of גריינץ mentioned in the Tosafot of Sens (to Pesaḥim).
Isaac is mentioned in the Tosafot (Yeb. 5a, 71a; Ket. 38b; Zeb. 73b; and frequently elsewhere), and Isaac ben Moses, in his "Or Zarua'," No. 739, quotes Isaac ben Jacob's commentary on Ketubot, a manuscript of which exists in the Munich Library (No. 317).
He is quoted on almost every page of the Tosafot, and in various works, especially in the Sefer ha-Terumah of his pupil Baruch ben Isaac of Worms, and in the Or Zaṙua of Isaac ben Moses.
After Rashi the Tosafot were written, which was an omnibus commentary on the Talmud by the disciples and descendants of Rashi; this commentary was based on discussions done in the rabbinic academies of Germany and France.