Pink is good. Yellow is normally infertile but as we all say keep-em cooking and see what happens.
If it is more than 3/4 of the way through incubation you should not be able to see much of anything when candling because of the baby would now be taking up most of the inside of the egg and you would not be able to see through it, if that makes sense. If they egg was pink to start then went to yellow some time later sounds like the egg stopped developing and is dead. That has been what I have seen. I try never to crack eggs open till they have doubled the normal incubation time as some can developed at a different rate.
Preston described it pretty good. They almost turn opaque or maybe blackish(that doesn't feel right, but sounds right). 2 weeks away from my last set of eggs hatching I could barely see any pink, saw no yellow and saw baby gecko foot! Apparently sometimes you can see the babies move in the eggs too!!
Dont be upset. Your gecko will lay plenty more. I had 6 go bad. I wish they hadn't but at the same rate I've already got 8 babies to deal with.
If you only have one girl and 5 eggs I would not move them. Last time I found eggs I found 6 in one spot and broke 2 on the way out and the other 4 died. Honestly, if they still look good I would leave them be
I was thinking along the lines of temperature fluctuations. If your eggs have been sitting in a spot for a while at a certain temperature and you move them to a different temp that it could cause and issue like mine where I had 4 eggs go bad. I honestly don't know how much this could matter but I figure if the eggs look good where they are then it might be a good option not to mess with them. Plus, with 5 eggs if the 1st and/or 2nd get eaten you will know to remove the eggs for sure in the future!