There are 4 files containing the various contributions, as well as the correspondence. They are, I think, a treasure trove of matter; unfortunately, as I have said above, never published, and now somewhat out of date. But surely some day a job waiting to be done: it would provide a wonderful cross-section of theological thinking in India in the 1980s (the correspondence dates from around 1985 to 1987, from my cursory glance).
I found the 3 items of De Smet: a two pp. typescript on Pierre Johanns; 1 p. on Thomas Aquinas; and 1 p. on Analogy / Laksana.
I resisted the temptation to copy other material, restricting myself to a 1 p. typescript by Hans Staffner on The Krista Purana of Thomas Stephens, and another 1 p. typescript by Bede Griffiths on Jules Monchanin, founder of the Shantivanam monastery at Kulitalai on the banks of the Cauvery.
But the other great find, and unexpected, was what I think is De Smet's study of "The Christian Encounter with Advaita Vedanta: A Study of Four Centuries," published as late as 2010 under the title "Christianity and Shankaracharya" in vol. 3 of the St Thomas Christian Encyclopedia of India, ed. George Menachery (Thrissur, Kerala), 22-42. The article is 20 pp. of fine print, large format, and perhaps corresponds to the typescript in the possession of Daniel De Smet, which is some 40 pp. plus.
The date of completion of the above is a problem, given that vol. 2 of the Encyclopedia was published in 1973, and vol. 1 in 1998, with vol. 3 coming only last year, in 2010. A cursory look at De Smet's notes in the published text reveals that it could not have been written earlier than 1976 (the most recent item there is 1975: see 41n65 Mattam and 42n121 Marathi Tattvajnana Mahakosa). However: in the 1980 article "Sankara Vedanta and Christian Theology" Review of Darshana 1/1 (1980) 33-48, De Smet says:
This survey of the attitudes adopted by Christian scholars towards Śāṅkara Vedānta in this century is summed up from a monograph (now in the press)[i] in which I have studied the four centuries of encounters between Christians and Vedānta beginning with Robert de Nobili (1577-1656).
This would seem to indicate that the piece published 2010 was ready in 1980. The note added by me [this is from the draft of Understanding Sankara: Essays by Richard De Smet, to be published by Motilal Banarsidass, Delhi], will accordingly have to be modified.