I emailed someone I know who is very into Cardiff history, and though he came up with a few newspaper cuttings that mentioned the place (and the poor water supply), but he didn't have a photo. He placed the houses somewhere closer to the bridge - roughly where it divides into three, in the bottom right hand corner of the photo.
My thoughts with this photo is that it surely must have been taken in the 60s or 70s - long after the Ferris Row houses were in use. If the only newspaper or court entries date from the 1880s, and nothing since, it's probably fair to assume that they fell out of use, and were abandoned or demolished? It's hard to believe the buildings would still be there, at the time this photo was taken. But you may well be right!
I can upload the items I was sent, if you think it might be of use to you. It does include a few names.