I don't think any serious historian will explicitly reject Wiesel's flaming pits schlock. That would be edging too close to denial.
"You're denying my Holocaust" is the original "you're not respecting my pronouns."
So it gets labeled as "symbolic" but anyone who believes in its literal truth is also correct. What's most important is that you believe in atrocity Holoporno of some sort.
Wiesel probably used the flaming pits because it corresponds to a more literal definition of "holocaust" as burnt offering.
Here's how E. Michael Jones analyzes it:
In describing flaming pits, Wiesel was adopting a trope which had already been accepted as evidence at the Nuremberg war crimes tribunal. Like the pericopes which make up the Gospels, the Holocaust Narrative is made up of tropes, which can be inserted at will to provide repositories of meaning. One can replace the other as the narrative develops in time, which is precisely what happened to Wiesel's burning pit narrative when it got replaced by the gas chamber trope after aerial photographs, released in 1979, made it obvious that there were no 80-meter-long flaming pits in the camps.
The Holocaust Narrative, p. 202.
Routledge also has a whole section on Elie Wiesel's flaming pits, "Problem #4: Burning of Victims in Huge Trenches," starting on page 108.
Hilberg bought into the flaming pits trope. Eventually, a French author settled on the fact that such claims are "symbolic," even though the "eyewitnesses" to flaming trenches say they were literal.
It is important to note how Jean-François Forges, the author of the French brainwashing manual for teachers, handles this claim by Wiesel. Not surprisingly, he falls back on the excuse that Wiesel is actually speaking in allegorical terms, not literal ones. First, completely ignoring the aerial photographs which clearly show that Wiesel’s vision is a pure invention, Forges tries to validate Wiesel’s vision by stating that other eyewitnesses also saw flames and smoke.
Elie Wiesel, Saint of the Holocaust, HH#30, p. 123.
When evidence converges to something convenient, it's called "corroboration."
When evidence converges to something inconvenient, it's "symbolic" or the eyewitnesses are diagnosed with mental/cognitive disorders.
In a bizarre book called
Fantasies of Witnessing, the author agonizes for dozens of pages how to address Wiesel telling two contradictory versions of how his father died.
But he also believes in the flaming pits:
As director of the President's Commission on the Holocaust, created in 1978, and a council member charged with conceptualizing the Holocaust Memorial Museum's permanent exhibition, [Rabbi Irving] Greenberg has played a major role in shaping Holocaust commemoration in the United States. In a paper presented at a 1974 symposium on the Holocaust, he offered the following dictum: "No statement, theological or otherwise, should be made that would not be credible in the presence of the burning children."
Perhaps no statement better captures the sanctimonious veneration of horror that so often serves to curtail rather than encourage critical thinking about our present-day relationship to the Holocaust. Such statements, it seems to me, promote a kind of dishonesty under the guise of virtuousness. Certainly, in the presence of the children who were thrown alive into the crematorium furnaces or burning pits at Auschwitz-Birkenau in 1944, no abstract statement, theological, philosophical, or theoretical, would be appropriate—including, of course, Greenberg's own working principle. But this is precisely not the context in which we make statements about the Holocaust, and pretending that it is limits and distorts understanding of how present concerns shape the historical past.
Fantasies of Witnessing, p. 215-216
"The sanctimonious veneration of horror"

I'm going to try to use that one more often.