The key lies in understanding the past perfect and the form is had + past participle.
The past perfect is considered as an early past. We go back for a moment whilst we are already talking about the past to clarify that something had already happened at that time we are talking about.
When I arrived at the party, Jane had gone.
Now think about that sentence -
NOW >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> PAST >>>>>>>>>>>>>>>>>>>>>>>>> EARLY PAST
(You arrive)-------------------------------------------------------------------------------------------- (Jane leaves)
Now your case -
You found out that had not known is not popular at all. Now considering this all, I think that when we talk about our perception such as knowing, the usage will be not that frequent as it'll mean that at that time (early past), that was not known to you. Anything hadn't makes it a special case. Let's get back to the same example to simplify it.
The things turns upside down if you use hadn't here.
When I arrived at the party, Jane hadn't wasn't gone (because, if she was there, it cannot be the early past!).
NOW >>>>>>>>>>>>>>>>>>>>>>>>>>> PAST >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> EARLY PAST
(You arrive, Jane wasn't gone) ---- (Jane did not go) -------------------------------------- (Jane hadn't gone)
If you see, it more depends on the context than the verbs you think that affect the use of hadn't + past participle. We can take some more examples and fit into this graph.
I checked Ngram and found that if you compare any did not (any verb) to had not (any verb), the use of did not is more frequent. The reason could be this only. What I tried to convey through the illustration. The Ngram clarifies that most of the times, we talk about the past and not early past (though it's not obsolete).
Swan's book describes another interesting thing...
The past perfect is common after past verbs of thinking and saying, to talk about things that had happened before the saying or thinking took place.
Examples -
I told her that I had finished (NOT... that I (have) finished)
I wondered who had left the door open