I'm guessing that Penny's problem is that she has noticed the join.

Flora T's writings are a reasonably coherent description of her experiences (wasn't there, or even born, but they are not incredible)

What I have seen of the BBC series was amiable enough, but codswallop, and only dimly related to the books.

As regards Penny's particular query, I would be somewhat surprised that the postman took any significant notice of such goings-on, I would expect him to condemn them all as being outwith his beliefs. Queenie 'discovers' a ritual? NO, either she knows one, or she invents one, but she's no researcher. She 'explains that paganism simply means things done in the country' NO, the postman is a countryman himself, and anyway that isn't so.

I looked forward to the LR production, unlike MM I had read the books, and hoped that something more than the title and a few character names would coincide. I don't remember how many episodes it took, but I didn't last for many.   Ah, well, perhaps I wanted too much.