On the subject of academic works being impenetrable to us plebs:
I must have joined a website called Academia at some point and they keep sending me emails of attached copies of theses and published papers. Whilst most of them are indeed very heavy-going for the likes of us, they can contain a goldmine of info, and we mustn't forget these people have been going into this from the far end of a fart so they leave no stone unturned.

The latest one was on the works of Ravenscroft. What I could follow was fascinating. All the evidence displayed which went into detail on his life story would suggest that all of the material in the 4 books came from other printed and manuscript collections and from contemporary plays. Whilst he was an anthologist like Child the material was largely London-based and was intended for the use of the well-to-do there. Of course that doesn't affect the half dozen or so pieces that eventually were recovered from oral tradition in later centuries.