WRdeS, Were the CSC then on St Mark's Road?
Braz Faleiro SJ talks about his experiences is this audio interview (conducted separately, and not as part of the Ramponkars' Archive... the latter is a good initiative) when I met him just in time to download his memories of those times:
https://archive.org/details/fr-braz-faleiro He talks about the teacher in question (whom everyone here knows is Matanhy, but with the Salesian school, rather than college). Also Christopher Fonseca, whom I guess you're referring to, was part of the CPI (not CPM, a big difference in those days when the Left was influential but prone to a whole lot of factionalism).
As far as Matanhy goes, he told me very clearly during the Protect Waters Protect Life March (circa 1986-1987, not sure of the exact year) that he didn't consider his politics to be anywhere remotely Leftwing, though he did participate and lead a number of protest and subaltern movements of that era.