Hi,
Some minor things:
There don't seem to be any tutorials on how to create certain popular features, including hardened platforms (hidden within the Attached Object Editor - not obvious), creating PBR materials, etc. These could expand chapter 3.
4.3 "In the options form you get set all the options of ModelConverterX." could be "In the options form you set all the options of ModelConverterX. "
"With the
Reset to default button in the toolbar at the top of the form you can reset the currently
selected category of options to their default values. With the
Reset all to default button you
can reset all options categories at once to their default values."
could be:
"The
Reset to default button in the toolbar at the top of the form resets the currently
selected category of options to their default values. The
Reset all to default button
resets all options categories at once to their default values."
4.3.x Have an odd format; could have a layout that would be easier to understand. EDIT: I think these will be formatted later?
Example:
Current layout:
===== AutoSave =====
The AutoSave section allows you to specify settings regarding automatically saving certain files.
It contains the following options:
; AutoSaveEventLog : Determines whether the event log is automatically saved to disk as a TXT
file when you export an object. ; AutoSavePreview : Determines whether the preview image is
automatically saved to disk as a JPG file when you export an object.
Better layout?
AutoSave
The AutoSave section specifies settings regarding automatically saving certain files.
It contains the following options:
AutoSaveEventLog : Determines whether the event log is automatically saved to disk as a TXT
file when you export an object.
AutoSavePreview : Determines whether the preview image is
automatically saved to disk as a JPG file when you export an object.
Note: I usually think that manuals are better in the third person (i.e. "specifies settings") rather than 2nd person ("allows you to specify settings"). This is a personal preference and one you do not have to agree with.

I will no longer suggest those changes below, but there are others.
4.3.1 "MaximumUndoMemory: The amount of memory (in MB) that
can maximum be used by the undo functionality. If more memory is used the olders steps will be
removed and can not be undone anymore."
could be:
"MaximumUndoMemory: The maximum amount of memory (in MB) that
can be used by the undo functionality. If memory needed for undo exceeds this value the older steps will be
removed and can no longer be undone."
"CheckForUpdateUnstable" could instead be "CheckForUpdateDevelopment" (a change in MCX). Unstable sounds so scary.
4.3.2 Particles - isn't this really an Effects section, since PlaySounds has little to do with particles. (This would be a change in MCX.)
"ZoomScale" could be "MouseZoomScale" which would make it clearer what it does. (MCX change).
4.3.3 "Create empry LOD" should be "Create empty LOD"
4.3.5 "This should be false for FSX DDS files." Isn't this also the case for P3D DDS files?
"The texture is first searched in the folder of the object you are reading, after that all folder in the search path will be examined. " should be "after that all folders"
"You can use the special tags [FS2004] and [FSX] to entire paths depending on your FS installation folder." This is unclear, perhaps you mean "You can use the special tags [FS2004] and [FSX] to specify the path to your FS installation folder." And there is no such tag for P3D?
4.3.6 "Having a small offset can give noise at lower mipmaps." Could this mean "Having a small offset can cause edge artifacts at lower mipmaps."
More later.