Sorry for your loss !! Its always difficult to loose a beloved animal.
I have to agree with others though, to cold to digest a rather large meal. It doesn't matter what others do or how long it worked out, it is risky.
Whether the animal is being tricked into thinking its winter or not, those temps simply don't support digestion. It slows it down so much that the rodents begins to rott before it is broken down sufficiently. Gases are released and the animal bloats. They try to regurge, but that in itself is terribly stressful for the animal and sometimes something inside bursts before they can get rid of the offending (and bloated) meal.
2 days into digestion, that rat should have looked far broken down, instead it looks basically un damaged.
Perhaps other animals did ok, but I think it was luck. In the wild they instinctively fast when its to cold for digestion. Or they find a "sunny" spot during the day where the heat goes up quite a bit, even though its "winter". In captivity they do not have these options.
If I were to do a "season" I would only do it for adults (for breeding) and I wouldn't feed during these cold temps.
I know you don't agree, but you did ask for thoughts and opinions...
I'm sorry to hear you lost another animal. Could it be due to the feeders ? It may, but haven't you fed others with these rodents? Did the rodents look/smell ANY different ?
My thoughts are that perhaps since the last feeding the ambient possibly went down just a few more degrees then it normally was ? At these colder temps it wouldn't take much to disrupt digestion enough to cause severe issues. They don't all try to or are able to regurge.
Anyway, its a thought.