Candling

I think I am going nuts with worry and thinking I am doing everything wrong... This morning when I was going to turn the eggs, they felt cold although they had been in the incubator all night.
During the days they kind of keep around 37.5 by themselves it seems, but during night with the same settings for air conditioner and the incubator the temperature drops to 35 for some reason.
I have had as low as 33 even for periods of couple of hours, so I am not sure if the hatching is completely ruined or not. There has also been 3-4 short, maybe 5 minute periods of too hot temperature, and I am not talking 38 or 39, I am talking up to 42.... Super worried and starting to stress. At the same time when I google things half of the people say it is super easy and eggs hatch even with lots of mistakes and mess ups, while the other half say it is like rocket science and even the slightest deviation will kill the embryo. I want to believe the first group because partially it is easier and partially I cannot believe farmers could have been successfully hatching eggs artificially for ages without all the technical advancements if it was this difficult.
Did not get my finger out to make a candling box, so still using flashlight. But nothing can be seen... only that makes me want to abandon the whole thing.

Hmm.. seems homogeneous to me

Day 5 for this egg...maybe not much to be seen?

This one has a yolk...

7 days old egg...

Again... Not sure at all if I am supposed to see anything as the eggs are araucana eggs. OR what I am supposed to look for. But at least I can see the yolk. First I thought it is just the shadow on the side that is farther away from the light source, but it slowly floats to the top when I turn the egg, rather than just moving immediately. So I guess it is something inside the egg and not just shadow.

The only thing I am certain about is that I am worrying way too much.