A major impediment to reaching a consensus about the Book of Mormon is the magical world view employed by those who advocate a Mesoamerican setting.
I just returned from the Mormon History Association's annual conference which was held in St. Louis. One of the speakers was D. Michael Quinn, who wrote the book Early Mormonism and the Magic World View. I've found the book very helpful in some respects and I've cited it, but it's also problematic because of the unstated assumptions upon which the basic thesis relies.
Instead, I'm going to discuss how the Mesoamerican theory relies on its own Magic World View. (I think of the search for a Mexican Cumorah as a Magical Mystery Tour, or, more precisely, the Magical Mesoamerican Tour.)
I'm not being facetious here, at least not entirely.
To the extent I'm getting pushback on the two-sets of plates scenario, it's from people who think the Lord intervened supernaturally, which is a euphemism for magically. For example, on Sunday I did a fireside in Nauvoo. One of the questions involved the plates. It was a great question. The individual opined that the Lord could have done anything he wanted with the plates; e.g., taken them to heaven, transported them anywhere, etc.
I replied that metaphysics doesn't seem to have been in play when Mormon and Moroni created the abridgment and Moroni buried the plates in the stone box before he died.
The magic world view can't explain why Mormon and Moroni went to such trouble. The Lord could have created the plates out of thin air and put the stone box near where Joseph lived anywhere. No need to nudge the family to Palmyra, etc.
It's axiomatic that the Lord could do whatever he wanted, in accordance with natural laws. But it's also axiomatic that the Lord doesn't intervene except when absolutely necessary, and even then obliquely. Any theory that relies on golden plates being taken to heaven or magically transported long distances needs to address the work and effort that Mormon and Moroni expended on compiling and preserving the plates.
I think (hope) there's a consensus among all LDS that Joseph Smith obtained a set of plates from a box made by a mortal Moroni out of stone and cement.
Are we good with that?
If we read the accounts, the stone box contained a set of metal plates, a breastplate, and a set of spectacles or interpreters, all of which were resting on elevated stones.
If someone disagrees with that, please let me know by email ASAP. [I realize that the North Visitors Center depicts the sword of Laban and the Liahona in connection with the stone box, but that's because the historians who consulted on the project conflated separate accounts and cannot explain those artifacts except by magical thinking about the stone box, as I'll explain.]
In December 1827, Joseph took the plates (what he later called the "original Book of Mormon") to Harmony, PA. There, he translated the book of Lehi with Martin Harris and probably Emma and her brother.
Are we good so far?
In June 1828, Harris lost the 116 pages of Lehi. Joseph didn't resume translating until winter 1829, mainly with Oliver Cowdery as scribe. They translated all of the plates (except the sealed portion) by the end of May, 1829, because Joseph translated the title page, which was the last leaf of the collection of plates, and had it printed and sent to the federal court in New York as part of his copyright application so it arrived by June 11.
Here's where some of the magical thinking has crept into the traditional narrative.
Many scholars have assumed that the original plates of Nephi were somehow included in the record Joseph got from Moroni. They know the title page doesn't mention them. They know Joseph translated the title page before he translated the plates of Nephi. And they know the title page was the last leaf of the collection of plates.
But they surmise, based purely on speculation, that he somehow skipped over the plates of Nephi to translate the title page first.
[I should point out that many LDS scholars and educators, including historians, currently think Joseph didn't even use the plates when he translated. They claim they were under a cloth the whole time, as the latest Church history movies depict. So far, none of them have explained how Joseph could say the title page was a literal translation of the last leaf of the plates. For these scholars, the entire translation was part of the magic world view. I think Joseph actually used the plates during the translation. It required him to study the characters and learn what they meant, but he also had to rely on the seer stones (the Nephite interpreters as well as his own) to confirm the sequence of words he formulated. Bottom line, I don't think the plates were merely window dressing.]
Next, we know that before leaving Harmony, Joseph gave the plates to a divine messenger. He, David and Oliver met a messenger along the road to Fayette. The messenger had the plates and said he was going to Cumorah.
If you have a Mesomania magic world view, you think David was lying or confused when he related this story multiple times. And yet, this was one of the Three Witnesses who had a reputation for honesty and accuracy (which is why he was chosen in the first place). Plus, there is reason to believe he related that story as early as 1832 (and probably sooner).
If you take David at his word, then the messenger was taking the Harmony plates to Cumorah.
The obvious answer is to return them to the repository of records (Mormon 6:6). I can't think of another reason, and I don't know anyone who has. Instead, the Meso magic world view simply denies the event occurred because it contradicts the world view of Mesomania.
And this is how it is depicted in the new Church film; i.e., it's not depicted at all.
It think you get the point now. We know Joseph obtained the plates of Nephi (colloquially called the "small plates of Nephi") when he was in Fayette. the question is how and when. I think the messenger brought them over from Cumorah. I'm interested in any alternative explanations that don't involve the magical thinking that David was a liar/deceiver.
I'll skip over other details to get to the main point about the repository in Cumorah.
The Meso magic world view requires you to believe that there was no repository in the New York hill Cumorah. You have to believe either that (i) Brigham Young, Wilford Woodruff, Heber C. Kimball were also lying, or (ii) that it was a magic chamber that Joseph and Oliver visited at least three times even though it was actually in Mexico.
There's plenty more to discuss, but for now, I hope you get the idea.
Letter VII and the two sets of plates are pragmatic, real-world explanations for the events in Church history that cannot be reconciled with the Meso and other non-New York Cumorah theories. The New York setting for Cumorah is uniquely capable of explaining these events without resorting to a magic world view.
IOW, Mesoamerica requires acceptance of the Magical Meso Tour, searching for Cumorah in Mexico, as well as the Mesomania magic world view.