There is no evidence to suggest that it is anything more than a lie or at best the unconscious remembrance of what someone experienced or was told, with the actual empirical source forgotten.
Transcendental knowledge has no consistent relationship with truth.
In fact it is typically thought to be true regardless of the facts. The acceptability of transcendental knowledge is best understood when it cuts against you rather than for you. For example, what if I told you that I had transcendental knowledge that you were guilty of murder regardless of the facts. Your sentence is to die by being burned at the stake immediately. Knowledge which is unprovable and irrefutable because it is foisted off as transcendental has no place in science.