Trying to customize debian 11 with cubic and a preseed file : the preseed file is ignored

Hello.

I'm working on a method to add any parameter I may need now and in the future to debian without the installer make some questions to final user and maybe I found it,thanks to the help of some good reddit users that put me on the right path. The method is called "Automate the installation of Debian with a preseed file". Basically I should create a preseed.cfg file that I should add inside the Debian ISO image so that the installer will read inside of it and it will automate some settings during the installation. My doubt was : how and where to place the preseed.cfg file ? I've found part of the solution by watching this video tutorial :

https://www.youtube.com/watch?v=QdA7UX5VJjc

and this github :

https://github.com/Nidouille/Debian-...d-Installation

Anyway I think that I should modify a little bit the instructions because I'm using Cubic. This is what I did. When Cubic starts a new project,it creates 2 folders :

custom-disk
custom-root

Below you can see what are the subfolders there are under the custom-disk folder :

https://ibb.co/vhzZgwg

You can see some interesting subfolders,like : d-i and preseed. Inside the preseed folder I have placed the preseed.cfg file with this content :

d-i debian-installer/add-kernel-opts string intel_iommu=on
d-i passwd/root-password password marietto

The author says to do something like this :

Ajout du fichier de pré configuration dans initrd

So,I tried to do what she says,with some little differences :

chmod +w -R custom-disk/d-i/
gunzip custom-disk/d-i/initrd.gz
echo preseed.cfg | cpio -H newc -o -A -F custom-disk/d-i/initrd
gzip custom-disk/d-i/initrd
chmod -w -R custom-disk/d-i/
cd custom-disk
chmod a+w md5sum.txt
md5sum $(find -follow -type f) > md5sum.txt
chmod a-w md5sum.txt
cd isolinux
chmod a+w isolinux.bin

Anyway cubic says : "the vmlinuz and initrd file have been automatically updated to match the selected disk boot kernel". I assume that the steps above aren't needed and that they are performed by cubic automatically.

At this point,when I tried to regenerate the iso file,I saw that cubic detected the preseed.cfg file as well as some other configuration I did,as you can see below :

https://ibb.co/mSZYrW5
https://ibb.co/KwXK40L
https://ibb.co/DVJkFFF

The problem is that all the config files that I have inserted inside the ISO image are ignored and when I have installed the customized debian physically on my disk I didn't see one of the modification I want,that the installer does not asks me to choose the root password. It asks it,so I presume that it does not work. Regarding the other change I want,to add the parameter intel_iommu=on,is added,but I think that it does not read it from the preseed file,but it reads it from the boot/grub file and/or from the isolinux/menu.cfg file.
Cubic also says "reference these files (I think the preseed file in the disk boot configurations) by prefixing them with /cdrom". This indication is too vague and does not explain really how to do that. Or at least,I don't understand what should I do. Maybe the reason why it does not work is that I didn't do that.