There are many hymns that appear in Henkel's hymn book (https://hymnary.org/hymnal/CHBC1838?page=0) not found anywhere else but in the other editions of the work. Would it be safe to assume these are hymns by Henkel?
According to the preface, Henkel's texts are marked with a symbol
I compared the first hymn in the book with Joy to the World in the book, and the first hymn had a ‡, double dagger symbol. I checked this with another hymn explicitly marked as Henkel's in Hymnary, and it had it too.