Sellers lists several dozen New Jersey gunsmiths, but most of them are from the machine age. Listings for patent holders for revolver systems, etc. Also, keep in mind that Sellers culled existing records and printed what he found. All of his sources are not of the same quality. He was good about telling readers where his stuff came from, so you can evaluate it yourself.
I was looking for builders of Kentuckies, not the rest, so I made some arbitrary exclusions. Anyone post-Civil War active was excluded unless cited as a builder of our guns. If they died during the Civil War I included them because they could have been building Kentuckies prior to that. I am 1/2 way through the book and here's what I have in addition to Annelly and Cowell.
Scott Allen, Baptistown, died 1860.
Cornelius Austin, Armorer to NJ, 1776-1779
Aaron Baldwin, Newark, 1841-1842
John Barr, Camden, died 1850.
S. Bodine, Camden, died 1850.
Alexander Boyden, Newark, 1824
Peter Crae, Patterson, died 1860.
Peter Dalton, Jersey City, listed in 1860's as maker of percussion 1/2 stocks
John Fitch, Trenton, 1743-1798. (likely an armorer)
In sum, maybe some armorers and a scant few late-percussion possibilities, but not one flint builder of any reputation or note.
There's an old joke around here that there are only two parts to New Jersey, that part which is outside of NYC and that other part that is outside of Philly. Maybe there's more truth to this than humor, at least regarding guns.