IMO there's nothing to be lost by waiting. The incubator is in use regardless and them being in there doesn't hurt anything. If there are signs of life you could give them a pinhole into the air sac. I don't do more than that. Others do and are sometimes successful. Usually if I think they're dead, they're dead. I give them an extra day then toss them. I do not like twisting little heads off because something turns out to be horribly gone-amiss. I would rather nature take her course. But mine are livestock--not pets, though I do enjoy them very much. Pets are a whole different thing and I completely understand why folks want to do all they can.
I usually ignore elevated humidity unless it lasts for hours. If it were at 80% though, I would open the incubator, take the lid completely off, and pull up the corner of the bottom layer (mine is plastic needlework canvas). I tilt the incubator toward me and sop up the excess water with a towel. I haven't ever had it that high, but I've done this on occasion for persistent 60%. A day-long spike isn't going to kill your babies, but it's less than optimal. Lots of people incubate dry for non-waterfowl--I don't, but our ambient humidity is usually pretty low, especially inside the house.
What do you still have hatching?
