I Chatted with the priest for some time. Surprisingly, there was no hesitation on his part to accept the theory of Jain temple taken over by Hindus. Further he threw some more light into the theory as below:
“This used to be jain centre (temple?) main carving on the wall is of Parshwanath” and the devi is said to be Padmavathi (a jain goddess).
When Hindus took over, we considered (sankalpam) Parshwanath as Bramha, Padmavathi as Bhagavathi and other two deities on the left and right of the devi as Ganapathi and Siva”
There are a few idols kept outside which is believed to be sarpakavu or nagarajas / naga yakshis.
Interestingly, there is no sign of demolition of any structures / idols. Only some additions like pavements, Mandapam and sopanam steps and designs on both sides of sopanam seem to made so as to suit to the hindu style. That means due to some reason, the jains might have abandoned the place centuries ago and would have been occupied by the Hindus only recently. That may be why the priest is able to explain the story correctly.