SK you are completely depend on Buddhist scriptures. E.g "Pacceka Buddhas do not have have the capacity to teach most of what they have understood" -How do you confirm about "Pacceka buddha"(or label induvidual as pacceka Buddha.) and his attainment and achievements in spiritual life. you rely on scriptures those old as 2300 years and written not by Buddha it self and there are so much hindu influence on it.

Buddha himself taught us not to completely rely on scriptures in kalama sutta.

Kalama sutta allows for accepting teachings on faith if they are praised by the wise. Kalama sutta does not tell you to assume the egoistic position that you are capable of knowing everything that is possible with your current state of mind. If you want to verify if someone is a Pacceka Buddha, you have to become a Buddha yourself or at leasat be able to read others' minds.

Like I said before, if you are looking for a scientific method to prove it, you are never going to get one. You need to verify it the Buddhist way.

The suttas have be verified and purified by so many Buddhist councils throughout the history. They are designed to remove alien teachings.