She describes the composition and/or the feel of the plates and also the part she played in the translation and some of the details concerning the time she spent helping in the translation.
I suppose what you're saying is that because she did not tell the truth in regard to Joseph's practice of plurality of wives then she shouldn't be trusted with what she said about the plates and her part in the translation. As I read the complete text of the 1879 interview, I believe that there was and/or may have been a compartmentalization which was taking place/occuring in Emma's mind. Polygamy was a practice that had cost her dearly. Whether she was reframing, forgetting, or protecting, it’s clear she was speaking from a place of pain. Her testimony may have been and internal negotiation between what happened and what she could bear to say. As many years had passed since this time of trauma she may have seen this also as a time in which she could shield her family and new faith community from a divisive legacy.
On the other hand, Emma’s testimony about the plates is tactile, mundane, and tied to her domestic role. It’s not emotionally fraught, and she had no reason to distort or hide it. Also, her tactile description is consistent with other witnesses.
Emma’s testimony, in my opinion, was a blend of faith, belief, trauma, loyalty, and memory. She may have honestly thought at that point in time that she had good reason to withhold the truth in regard to polygamy and yet tell the truth in regard to the plates. More or less a coping mechanism within the framework of her current life trajectory in 1879.
Beyond that, I don't know that I have anything else to contribute on this score. It's a matter of how one thinks this little snapshot of time fits in with the larger bird's eye view of the Restoration and everything that has come about since that time.
Regards,
MG