In 1984 a Eastern Syriac Manuscript called “Spiritual Discourses and Other Works Of Mar Isaac of Ninevah” was found in the British Library. In 1994 the first four chapters were translated into Italian by P. Bettolio and subsequently the remaining chapters were translated in various languages including English. The English version of the second part is available as ISBN-13# 978-9068317091.
I found a copy of the first part in Italian at Zlibrary. I used a machine translation and given my limited knowledge of Italian and knowledge of Spanish corrected it as best I could.
The scholarly consensus seems to favor this as an authentic, heretofore unknown, work of St. Isaac of Ninevah subsequent to his well known work, The Spiritual Homilies.