Sections of the bulwarks could fold down as needed, giving the pivot guns good arcs of fire on either side, but it does appear that the bulwarks at bow and stern were fixed, so the guns could not fire directly forward or aft. I would guess that was for seaworthiness, since folding bulwarks could never be completely watertight, but it is a bit odd in one sense; the rationale for double enders was to operate in narrow rivers or channels where ships couldn't turn around, so you'd think they'd want to be able to fire directly ahead.
Although they had rudders and pilothouses at both ends, bow and stern were distinctly different, so it's legitimate to use those terms. The US Navy also purchased a number of ferryboats which were true double-enders.