We don't answer homework questions on this forum. The way you introduced this question, I'm not clear on the format. It sounds like this is not an individual topic research paper, but a paper topic/project assigned by the instructor. I would consider that homework. If this is your own original research, then that might be different, but in that case maybe you could pick clearer examples.

Regardless, I'll share my judgments: I'd accept either of the second readings in each pair, deontic or epistemic. However, that would be for the form "must not", which is more natural in (my) American English. "Mustn't" sounds either British or archaic/formal to me, and it's something I would never say. So I don't know if my interpretation of that contracted form is reliable. Still, I can imagine interpreting it that way.

But again, if this is an assigned topic from your teacher including that data, then there may be a "right" answer based on what your teacher said, and my comments/judgments here may be irrelevant. (Another reason that real-world data from the internet doesn't always help with homework problems.)

OK, that's fine. (We get a lot of homework questions here, and it's important for the teachers, and for the students, that we not do homework for anyone. Background information for research papers is a different issue.)

So, yes, I would find both acceptable, with the epistemic sense along the lines of "I have observed your general ignorance, so I believe that you must not read a lot of books" (or whatever similar context would lead to an epistemic generalization of that sort). Again, with the caveat that the "mustn't" form isn't natural for me. (And that really may change the available readings for those who would use that form.)