>> The JST doesn’t claim to be an alternate translation of existing texts, it claims to be a restoration of the original text received by revelation. You are being mislead about what the JST is. <<
LSD itself claims to be a restoration, but the version of scripture claims to be an “inspired translation,” not a restoration.
>> It is made clear in the introduction. <<
The introduction makes clear that a restoration is involved, yes. But, given the absence of any reference to restoring missing verses to Genesis 50, that seems to refer to restoring a proper interpretation / translation, not to restoring missing verses to Genesis 50. This is particularly troubling, because the introduction broaches the topic by discussing the restoration of Matthew. It’s like walking into a bar, and surrendering your holstered pistol, but not the one in your socks: it gives the impression you’re disarming yourself, without actually doing so.
I actually did re-read the introduction, preface, etc., before commenting to see if I was missing something.
From the intro:
...The Lord inspired the Prophet Joseph Smith to restore truths to the Bible text that had become lost or changed since the original words were written
It seems pretty clear to me that in order to restore things that had become lost, you would have to add them back in.