I believe there are at least three falls between the E Fork of the SG and Upper Fish Fork Camp.
Take a look at
this map of the Upper Fish Fork Camp area. Point "A" is the approx. location of Upper Fish Fork Camp. From there, I've been down to the point where the canyon really necks down, approx. at point "B". There is definitely a waterfall here. I crawled out on my belly as far as I dared. I could see water shooting out into space, but I could not see the bottom. There was a cool breeze coming up the falls. I got the impression, and it's just that, an impression, that the falls were of a pretty good height. I saw no way, with out technical equipment, to go down those falls. The canyon was very bare there; it was essentially water scoured rock.
I know there's another falls marked on the map, as you have pointed out.
There's yet another falls down closer to the E. Fork.
That's at least three falls. I imagine there could be another one in there some where. Whether or not it's great for canyoneering, I cannot say, but the fact that there are falls at both the upper and lower "entrances" to Fish Fork means that the area is some wild, seldom visited country.
HJ