Words of Mormon 1:9
9 And now I, Mormon, proceed to finish out my record, which I take from the plates of Nephi; and I make it according to the knowledge and the understanding which God has given me.
He states that his understanding is from God. Not from man. There is a difference so big you must experience it in order to fully understand what is being said here.
Mormon here informs us he is going to finish his records with material from the plates of Nephi. This includes the sealed portion of the plates we don't currently have. But Mormon knew about the sealed portion, and knew what content was there. I'm sure it influenced his thinking and much of what he wrote, how could it not? It's been said the Book of Mormon is still a "sealed" book to some extent aside from the sealed portion that Joseph didn't translate. Is the part we have sealed? Sealed in that we don't get it's full message?
Way I read it is there are things we must do in order to penetrate the seals in place on Gods word. The method is the same as it was for Nephi and the Liahona, faith need and diligence to what it says (1 Nephi 16:28). Talking about the directions on the Liahona once a week I don't think worked for them. And that ties into the church being put under condemnation for neglecting the Book of Mormon. It's got to be more than talk and an occasional out of context quote in a conference talk. In the doing, the understanding opens to the mind. I don't know that finding archaeological evidence to support the authenticity of the book is going to remove the condemnation either. As an analogy, in the medical setting no matter how hard I try and prove that a patient has one illness or another, or how much evidence I present about the accuracy of my position, no matter how much research I do, it would still be possible to completely neglect the patient, and not give appropriate care, treatment. You have to do something.
I enjoy the research too, don't get me wrong, lots of it is relevant to unfolding history. I just think the neglect the Lord refers to refers to a different kind of neglect than how many books of Mormon we distribute around the world, or whether or not we can prove with physical evidence the books' origins. A testimony of God's word doesn't come via that sort of thing anyway (Moroni 10:5). This is just my current view. There are probably other valid views.
"According to the knowledge and understanding the Lord" gave Mormon. I think Mormon followed the instructions in Alma 32. I think the seed was planted, nourished, grew and the knowledge and understanding the Lord gave Mormon increased and increased until he plucked from the tree of life. In fact he planted the seed of his own tree of life which lives now inside him. It is now his. And now he desires to share that which is more precious with us. But won't work well if we just proclaim the book is true and never follow the same steps he did and receive the same eternal perspective and promises.