Frogs don't... hide illnesses, as a rule. An active infection that's damaging the heath of the animal is pretty apparant in a very short time frame. I have no idea where this "they hide illnesses" stuff is coming from but it's blatantly untrue.
The stress placed on an animal by the shipping process and whatever handling or environmental conditions it is experiencing can cause a relatively passive bacteria load to turn into something more agressive and unchecked, but this would not have been apparant to Ed at the time of shipping and the frog would not be visibly sick.
Tissue breakdown in amphibians is extremely rapid after death, a necropsy isn't worthless but it is certainly worth less than it is for other types of animals. Inherently predisposed towards being less accurate to begin with, the second round of shipping and unknown timelines and conditions make the validity of firm conclusions questionable.
Humidity is water that is present in vapor form in the air. It is possible for an enclosure to be wet- covered in liquid- but still not humid. One does naturally link to the other but they are not automatically mutually inclusive, it's just very probable that the humidity was above the normal range for keeping the species. That said, soaking wet is worse than too humid when it comes to bacterial blooms, fungal growth, a reabsorbtion of waste matter through the skin, the spreading of various household chemical toxins and so on.
While it's not as good as a firsthand inspection, she looks to be in decent health from what was photographed in the shots upon arrival. Timpanic roll is within a healthy range, not obese but far from underweight, no discoloration or heavy sloughing of the waxy cuticle, clean clear eyes, nose and mouth, no visible abrasions, normal posture and body position for a whites that's awake and horizontal.
I wish there was a copy regarding how you inquired about the gender- the wording of Ed's PMed response seems to indicate that it was a response to a question and he qualified his answer with the reasoning behind the determination. The females very, very rarely call and it's widely considered to be an acceptabally accurate (while falling lower than 100%) method of casual sexing for the species.
Out of curiosity, how many frogs have died under the care of the thread starter out of how many owned? Which species have died, after how long and in what conditions?