This supposition, within Lewis*, seems popular, but there doesn't appear to be any great physical evidence for it. The COFLEIN record for the church* doesn't suggest any archaeological work has been done there, and, indeed, there is a record for a early medievel chapel elsewhere in the village*. The only evidence is the name of the church - though this may well be a good pointer: Tyfrydog is not a particularly usual Welsh saint, and the naming may indicate a genuine association with this very early figure.