(1) Victor Knorre? The dozen or so known games against Zukertort have
him at 50% (last I checked) but I know nothing about the guy.

(2) The Campbell who defeated Barnes in a match (I think it's Joseph
G. Campbell)

(3) I was going to say Serafino Dubois but apparently you've already
written something about him, though I couldn't find it on the web.

(4) Boncourt (I couldn't find a first name for him either)