Not sure whether the fish or I are more stressed.
After the lights came on, I noticed that the female tetra with the healing wound had developed some fungus over where the pustules had been last week but which had burst/subsided of their own accord - it looked as though a scale was attempting to grow over the open-but-superficial wound but this was accompanied today by fluff. So, conscious that I was looking for an excuse to simultaneously treat the male tetra with the still-cloudy eye, I tried to catch them to treat them together.
It was clear after a few minutes that I needed to remove all the plants and driftwood in order to do this. While the harlequins were volunteering to enter the net and had to be released, the tetras were darting away at lightning speed. It also became clear that it was a 2-person job, especially to identify and catch the male tetra. Eventually, Mr FCMF managed to disengage himself from a film to help and eventually we caught all 3 of the male tetras and had them in the QT with the healing-wound tetra, with the intention of putting back the two healthy male tetras into the main tank. Suffice to say that this was harder than it looked and somehow the cloudy-eyed male tetra ended up back in the main tank by mistake, not helped by the fact that there were only 1.5 people working on this as the other 0.5 was distracted by the film, while it was as though the cloudy-eyed tetra disguised his cloudy eye just before capture in the QT (perhaps a self-defence mechanism).
Currently, we have the fluffy-wounded female tetra in the QT, everyone else back in the main tank with plants and wood reinstated, while I've had another couple of unsuccessful attempts on my own at capture with the plants and wood in situ - the leaf debris is certainly escalating while the water is becoming cloudier and cloudier from disturbed root tabs! Ideally, I'd like to treat the two fish together, so will probably make another attempt later - but, for now, I'm giving everyone a break from the stress, myself included!