In 1811 there's an Edward Trahar baptised in Perranarworthal to Hopson Woolcock and Mary Trahar. This is the Edward that ancestry think is correct but I'm not convinced. It would mean he was 16 when he married Jane Underwood (who would have been 26!).
These hints come from peoples trees and not documentary evidence so you are right to query it. Bear in mind it was a baptism and not a birth so he may have been born a few years earlier.
Have you tried tracing Mary Trahar to see whether she married.
ADDED
Have you located the marriage licence for Edward and Jane