Hi Hans. Welcome. The timeline seems to have been something like this:
1988 - Leuchter
1990 - Polish internal study
1991 - Leak to IHR
1994- Markiewicz paper (
https://www.codohforum.com/viewtopic.php?t=122)
I believe Germar has discussed these things in multiple books and articles. In Auschwitz Lies (HH#18), he has a chapter "Polish Pseudo-Scientists." Apparently what happened is that after the Leuchter bombshell, the Poles did their own internal studies but decided not to publish them. But an insider who was sympathetic to revisionism (or perhaps just honest) sent photocopies of some of the results to a revisionist.
Here is the IHR's article from 1991 on the leak.
https://ihr.org/journal/v11p207_Staff.html
And here is part of Germar's commentary:
These results seem to suggest that samples from the alleged homicidal gas chambers contain considerable less cyanide residue than samples from delousing chambers, or even none at all. There are two things with the values given by Markiewicz, however, that struck me as odd:
1) The Polish original of this table gives cyanide as mg of potassium cyanide per 100 g of sample material instead of the internationally standard of mg of cyanide per kg of sample material.
2) The Krakow analytic results of samples taken from the delousing chamber are a factor 10,000(!) lower than results of samples taken from there by Fred Leuchter and by me. Apart from this, all values are below the detection limit of the method of analysis used by all professional analytic laboratories in the world (app. 1 mg/kg). I therefore assumed already in 1993 that the Poles committed a methodical error. (HH #18, pg 47-48)
So I think you are right that the concentrations in the leaked report are vastly lower than what Leuchter and Rudolf found. In the 1994 Markiewicz paper, the results are also really low and it is because they tested so as to exclude complex iron cyanides like Prussian blue in favor of only testing less stable cyanide compounds. From Germar's comment above ("already in 1993") it sounds like the earlier 1990 report had the same issue. (They may also done some tests with Prussian blue included, but if so this was not included in the 1994 report or in the 1991 leak).
In layman's terms, you could say Leuchter and Rudolf reported total cyanide in the wall samples whereas the testing method used by the Poles excluded over 99.9% of the the cyanide.
Why would these results be controversial if they were leaked as they show relatively modest readings?
Good question. I would guess that they didn't want to report super low values for the "gas chambers." Germar: "The only “positive” result of a sample taken from a room that according to the Museum had been a homicidal gas chamber is no. 15. No other samples contained any detectable residues." (pg. 47) But then after the leak, they probably felt compelled to publish something to put their spin on it, and that led to the 1994 report.