Leaving the buns overnight made no difference.

I thought again about throwing them out but Adrian convinced me to bake them after all, because why not.

Some of them (I had four trays full) rose a bit in the oven – not to the level of fluffiness I’d expect, but there was a definite improvement. Others came out almost as small as they were when they went in. I tried one, and while the texture was disappointing, there was nothing wrong with the flavour. Good enough that I ate another one. I guess they can go into the freezer instead of the compost bin. I just need to remember to have the right kind of expectations when I take them out to eat.