A very interesting detail about the synagogue's location is recorded in an article by E. I. Hallegua that appeared in the 1906 edition of the 'Jewish Chronicle' (Malabar Jews-I, October 5, 1906-Jewish Chronicle, p. 20). He describes that the Cochin Angady (Kochangady) Synagogue was established in 5105 A. M. (1345 AD), about a mile south of the Kadavumbhagam Synagogue (Mattancherry) and writes "at present only the four walls attest the site of its grandeur". This is a very crucial information, which I was not aware until recently (September, 2019). Not only it gives a precise location of the synagogue, but also attests the fact that the synagogue's four walls were intact in early 20th century. Another insight is from Rabbi Louis Rabinowitz who visited Cochin in 1952. We don't know what he meant by "of the 1344 Angadi edifice only ruins remain," (Far East Mission, p. 134)-perhaps he was only mentioning about the foundation stone of the Kochangadi Synagogue, if not, we have to assume that the ruins of the synagogue were visible until the mid-20th century!
As we know that the three synagogues of Mattancherry (Paradesi, Thekkumbagam and Kadavumbagam) align in a line (see 3, 6 and 11 here, and the Map 1 above) and are near the sea, could the Kochangadi synagogue also be placed as a continuation, and east to the mosque towards the sea? Ruby Daniel mentions in her memoir (p.10) that the synagogue was a few furlongs to the south where Jew Town of Mattancherry ends. There is a high chance that the synagogue and mosque were close to each other. Hallegua's pointer that the synagogue was one mile south of the Kadavumbhagam Synagogue nicely corroborates with this location. It is said that the Jews of Cochin donated wood for the construction of Chembittapally in Kochangadi! Most probably, the Kochangadi synagogue was located somewhere between the Dar al Salaam Road and Kochangadi Street, which continues from the Jew Street of Mattancherry (yellow dotted circle in map 1).