I feel I must chime in on this discussion - despite me having to use Google Translate to understand it!
Maybe you guys should study my work on composites and composi-stop builds in GrandOrgue. I have made dozens and dozens of GrandOrgue organs, some of which I have shared here!
When you attempt to make builds that use the extremes of pitchtuning the result is extreme distortion on the reverb fields. When you do this, you then have to create ranks that remove the releases altogether or substitute other releases in its place. If you do not do this you then have to tolerate reverb lengthening of pitch lowered ranks or the reverb shortening of pitch raised ranks!
Dear Organist 117 - you must use the "perfect intervals" of pitch tuning to create organs that do not sound out of tune! For example for a Nasard you cannot use 700 pitchtuning -you must use 701.955.
However, there is generally no need to exceed a few cents in pitch tuning except at the extremes of the keyboard range.
Example 1: In creating a Trompet 16 from a Trompet 8 you can use the first 4 notes of the rank and set up 3 ranks - The first at PitchTuning=-400, The Second at Pitchtuning=-800 and the third at PitchTuning=-1200. This way only the first 4 notes of the Trompet16 have the maximum reverberation lengthening!
Example 2: In creating a Nasard from a Flute 4. Simply use PitchTuning=1.955 and begin the rank on FirstPipeNumber=8. In so doing this you automatically are raising the pitch by 700 (by using the 8th note of the rank) and then the 1.955 pitchtuning raises it further to the proper tuning.
This only works within the concept of the equal temperament organ of course - it does NOT work for Baroque organs. For the missing 7 notes then you can program 701.955 for those missing notes - where the reverberation shortening (on pitch raising) is no longer noticed!) and replace the missing 7 notes with a separate rank using the FirstAccessibleKeyNumber and FirstPipeNumber coding.
Just about any mixture, is possible to be created using GrandOrgue. I have created dozens and dozens of different kinds of mixtures including, Cymbales, Fournitures, Mixtures, Tierce Mixtures Etc. Etc. This is very easy to understand once you realize that you can borrow from higher notes within the existing available ranks to create these. For example to create a Mixture III 1 1/3 you can use an Octave 2 Rank to reconstruct the entire thing.
To create the Mixture III 1/6 (Corona III 1/6) would be extremely bright and not too useful (the designation of this implies that the 1/6 level is the pitch of the notes at the upper end of the keyboard) - Most mixtures do not even arrive at 1/6 pitch (2 octaves brighter than a 1 1/3 Larigot!) until much lower down in the keyboard range. Even the Cymbale III's that I have made to the 1 foot level are more than bright enough for most organ constructions. If you study the sample sets we have been given - a rank that is to the 1 foot level begins to almost be inaudible by the time you get to the upper range. Eg: Doesburg Piccolo1, Den Haag Flageolet 1 etc.
The first step in reconstructing any mixtures is to understand its construction - Organ Encylopedia of Stops is so helpful with this!
Further info:
To make a Tierce you must use PitchTuning=-13.69 and Begin the Rank on FirstPipeNumber=5. Then you can replace the missing upper notes in the rank with PitchTuning=386.31.
To make a Septieme you must use PitchTuning=-31.174 and begin the rank on FirstPipeNumber=11
Sometimes you don't even need to recreate the upper notes because you can construct a 54 note organ from a 61 note rank. This way you have 7 extra notes that allow you to create the Quint 2 2/3s and the Tierces etc.
Anyway, all the best with your builds. Let me know if you have any questions etc. or wish me to elaborate on any of these points.