So sad to hear about the poor hog. Well done for getting it to the vet, which probably saved it from more suffering. Sometimes badly injured hogs appear when they are too late to save, however hard anyone tries.
Re. maggots – some hog carers will try to save a hog with maggots, but time is always important in the first place and it can be a long recovery. I imagine there is always a judgement call and people likely have different opinions about the best course of action in some cases – those are decisions for experts. But, I would always be inclined to contact a hog carer/rehabilitator to start with, if at all possible – but I know that isn’t always possible.
Fingers crossed the other hogs all stay out of danger, but I have no doubt that if a similar sitution should arise you would recognise that smell (once smelt never forgotten) and know what to do.
But you did your best for the little hog and that’s all we can do. You might like to add the poor hog to the Big Hedgehog Map. I always think it is a way of marking that hogs life and potentially helping hog-kind in general. https://bighedgehogmap.org/ On a lighter note, you might like to add your other hog visitors to the map as well.
Good luck with the other hogs.