Basj,
Thank you for your prompt reply. Took me a bit of time to get back to you, but I figured out a hack that would provide same visual effect as if Fences would allow me to distribute shortcuts within a fence in a custom/particular way that is not dictated by any kind of sorting pattern as depicted in my original post.
However, before I get into the hack's explanation, let me state how disappointed I am about Fences not being able to accommodate such a basic functionality. First, for decades we have distributed our icons in our desktops in a way that reflects our individual workflows and the way we all think differently. Even if provided with the same software and commissioned with the same tasks, different people will organize their desktop in a different way. I have seen this at work for decades. The way people group their icons and the spacing/distribution patterns within a group are a reflection of how we think and it helps to optimize our workflow in such a way as to make us more productive/efficient. Second, being that Fences have been around for so long and gone through several versions, I would have expected this to be a basic feature. In some earlier versions of Windows, Fences was unnecessary since you could create a folder on the desktop, then dump some shortcuts inside that folder, and you could later open that folder (or keep it always open) and your shortcuts would stay distributed inside the folder in any way you had freely arranged them (yes, including spaces in between them), so long as the auto-arrange option was disabled on that folder. Windows would automatically remember for that folder whether the navigation panel was on or off, the size of the window, etc. Some of this is still possible but it requires registry edits. See this post: https://www.techsupportall.com/how-to-manually-arrange-files-in-a-folder-on-windows-10-disable-auto-arrange/
Anyway, enough of my rant.
This hack is very simple although a bit laborious (some [including myself] would even call it cumbersome).
Main Concept:
Use transparent-icon shortcuts to create spaces in between the application's icons that you would like to distribute in whichever way you want. See the image below to form an idea of what I am talking about. This is the same example I used in my original post, except I have added a faint outline to what otherwise would be totally transparent icons filling up the space between your "real" applications' shortcuts to give the illusion of empty space in between them. After implementation the resulting transparent-icon shortcuts do not show any outline and just look like empty space. In this example you would need 12 transparent-icon shortcuts.

Implementation:
1) Create a transparent icon. You can follow this tutorial (https://www.youtube.com/watch?v=fkuZqJCFaog), but instead use a transparent background with no image on it. Alternatively, you can download one that I already created here: https://drive.google.com/file/d/1eTXqCyMySPGh1DFv3PuFOIwz3pIcsf_x/view?usp=sharing
Save the transparent icon you created (or downloaded) to any folder. Remember this folder.
2) Copy the shortcut of a lightweight application (like Windows' Notepad) to the fence where you want to create a space between icons. On the properties for that shortcut, go and replace the icon for the lightweight application with the transparent icon you saved to a folder in the previous step.
3) Now we change the text of the shortcut to make it disappear too. Windows-10 uses by default a font called Segoe-UI. Use Windows' Character-Map application to find the character set for that font. See the picture below.

Scroll about 2/3 of the way and you should see a block of characters that are empty spaces. I selected the first one (code: U+2000. After you have selected the empty-space character, click the Select button and then click the Copy button. Now go to the properties of the shortcut to which you assigned the transparent icon in the previous step. On the General tab, there is a textbox where the shortcut's name is contained. Delete everything on that textbox and paste the empty-space character from the Segoe-UI set. Click Apply and then click OK. Now your shortcut should not only be transparent but should appear as if no text is being displayed.
4) To create additional transparent-icon shortcuts as needed, just copy/paste another copy of the now-transparent shortcut into the same (or any other) fence. The new copy will have the word/string "-Copy" added to the end of the shortcut's name. To get rid of it, go into the properties of that newly created shortcut and delete the "-Copy" portion of the name and paste another empty character from the Segoe-UI font set.
So, basically every time you need to add a new transparent-icon shortcut to any of your fences, the name of the Nth transparent-icon shortcut you add needs to have a sequence/string of N empty-space characters from the Segoe-UI font set. All transparent-icon shortcuts in all your fences (and outside any of your fences in your desktop) count towards this naming convention. In other words, if you need 10 transparent-icon shortcuts, the 10th transparent-icon shortcut's name should be made of a sequence/string of 10 empty-space characters from the Segoe-UI font set. One important thing to remember is that all your icons are still in the Desktop folder in your computer. Fences only changes the way in which they are displayed, but they are all still in your Desktop folder. That is why irrespective of where (in which fence or outside any of your fences [simply in the desktop]) a transparent-icon shortcut is located, to be able to avoid the "-Copy" word/string being automatically added to the end of a new transparent-icon shortcut's name, every new transparent-icon shortcut's name should be made of a unique number of consecutive empty-space characters from the Segoe-UI font set. If at some point you have lost track of what is the length of the sequence/string of N empty-space characters from the Segoe-UI font set required for a new transparent-icon shortcut have a unique name (and avoid having the "-Copy" word/string being automatically added to the end of its name), go to your Desktop folder and count the number of transparent-icon shortcuts in it. If you have followed the suggested naming convention you shouldn't have any problems.
Like I wrote earlier, this is simple in concept but laborious (or even cumbersome), but that’s' what you would need to do to deal with Fence's limitation when compared to the freedom you have in organizing your shortcut icons on the desktop (without Fences).
Implementing this functionality should be breeze if we had access to Fences' source code. Maybe in time I will create an open-source version of it.
For now, I am using the 30-days trial. I don’t know if I will keep Fences, given this existing limitation since the hack explained above is so laborious to implement and maintain, but hope some people in the community might benefit from using it.
Raoul