Hello, Tad, it is good to read a message from you again. You pose an interesting question which I have been pondering for decades. We have had debates on this subject before. It is clear to me that some apocrypha is in the Pali Canon. How much is apocrypha is a big question. There are questions that we can ask to help us narrow down the authenticity of suttas in the Pali Canon. For instance:
1) Why are there almost no references to Siddhartha Gautama's father in the Pali Canon?
2) Why did it all get filtered through Ananda who was Siddhartha Gautama's cousin?
3) What would compel Siddhartha Gautama's cousin, Ananda, to give up his ruling class position to join his cousin, Siddhartha, in his homeless, mendicant lifestyle?
4) While the term 'vipassana' is lionized in Theravadan Buddhism; nonetheless, it is a minor term in the Pali Canon, suggesting it is apocrypha, meanwhile Theravadans demonize jhana. Why?
5) The kasina has been discussed here, and by a few Theravadan Buddhists; nonetheless, it is a minor term, suggesting it is apocrypha.
In conclusion we can only test the authenticity of any religious literature by maintaining a fruitful meditation practice.