There's honestly something twisted about having Cass blow Elis several times. Even fucking her. Only to have her killed before going back to Aurora. Anyway, I finished checking this out.
Chain Horse appears and there's empty cages in Elis vision with Una. So that's correct. However, Cass shows up again in the red path. Even with Aurora as the wife. So I would say this thing affects all of the paths. Some Cass simp must've used Cass Mind Control on the dev and he put her in all routes.
Anyway, from what I checked. Dead Cass appears regardless of which wife you chose. The only variant comes in the form of if Cass was spared in the prison. To which the scene progresses as intended. It seems this bug was overlooked. Or the dev underestimated how many people actually killed Cass when making the scene.