Did the JST use Adam Clarke?

That is a real match. Clarke uses the word in his explanation, and the next verse records Elijah’s grievances. Both borrowing and an independent change are plausible.

You account for the shared wording and the alternative. Clarke’s explanation gives you a possible source, while Elijah’s words give both readers a natural reason to use the same word.

The shared word alone proves Joseph used Clarke.

A single natural word can arise in more than one way. See how Clarke uses it and what verse 3 says before judging how distinctive it is.

That is a more specific parallel. I would compare other versions and read the JST’s extra changes to see whether the move singles out Clarke.

You take the structural match seriously. Dickinson’s later edition puts the clause in the same place. Campbell’s 1826 edition keeps the older order, so the edition matters when checking Jackson’s comparison.

The JST changes extra words too, so the matching clause tells us nothing.

Adaptation can include both borrowing and independent wording. The shared move matters, and the alternatives affect how much weight it carries.

I believe God can guide someone using study and judgment. I would ask what Joseph claimed for the particular change before deciding what use of a source would challenge.

You distinguish a model of inspiration from the textual evidence. A claim that every word was independently dictated would need to account for a demonstrated borrowing.

If one edit came from a book, that settles the entire project.

One edit can tell you something about the process. The project includes different kinds of changes and recorded claims about revelation. Each broader conclusion needs its own argument.