The clue turned out to be "H.O. Mascarenhas" listed by De Smet among specialists to whom he sent copies of his doctoral dissertation in 1954: see his "From the Vedas to Radhakrishnan" 1994 1.
Strangely, I think it is this same Mascarenhas who is mentioned by Jose Cosme Costa as proposing theories of pre-Portuguese christianity in Goa.
Hubert Olympus Mascarenhas was a "fiery Indian nationalist" and a priest, besides holding a doctorate and being recognized as an Orientalist, according to what I have gleaned from the net.
- The Quintessence of Hinduism: The KEY to Indian Culture and Philosophy. Bombay: Fr Bento D'Souza, St Sebastian's Goan High School, Thakurdwar, Bombay 2.
- Konkannachem Apostolik Kristanvponn. Rendered into Kannada script by A.A. Saldanha. Dabul, Bombay: Betal Prakashan, 1960.
- Interview with the Editor of New Leader, reprinted in the Silver Jubilee Souvenir of the Archdiocese of Tellicherry, 1970, see http://thenazrani.org/feasts9.htm
- De Smet, Richard. "Sankara Vedanta and Christian Theology." Review of Darshana 1/1 (1980) 33-48 = Understanding Sankara: Essays by Richard De Smet (New Delhi: Motilal Banarsidass, forthcoming) ch. 27.
- De Smet, Richard. "From the Vedas to Radhakrishnan." 1994.
- Costa, Cosme Jose. Apostolic Christianity in Goa and in the West Coast. Pilar, Goa: Xavierian Publication Society, 2009.
- Gispert-Sauch, George. "Advaita as a Unique Indian Contribution to the Articulation of a Christian Vision of Reality." Relating We Journey: An Interdisciplinary Exploration. [Festschrift for Dominic Veliath.] Ed. Jose Kuttianimattathil. Bangalore: Kristu Jyoti Publications, 2012. 161-175, at 166-170: Advaita Re-discovered: Hubert Olympus Mascarenhas.