Changes in grub.cfg custom Ubuntu 22.04 ISO not present on boot

I'm trying to follow instructions on how to make autoinstall Ubuntu ISO, but however I modify linux line in grub.cfg configuration file during customization of Ubuntu Server 22.04 ISO, modifications get lost.

I've tried to modify original menu entry:

menuentry "Try or Install Ubuntu Server" {
    set gfxpayload=keep
    linux   /casper/vmlinuz  ---
    initrd  /casper/initrd
}

by setting it to:

menuentry "Try or Install Ubuntu Server" {
    set gfxpayload=keep
    linux   /casper/vmlinuz autoinstall ds=nocloud\;s=/cdrom/ ---
    initrd  /casper/initrd
}

and then repack ISO. I do it with livefs-edit which produces new ISO image. If I mount that image, I can see that the change is really there, so livefs-edit does what it's supposed to.

However, when I boot virtual box VM using that image, that menu entry looks way different, with a bunch of other parameters, but with mine missing.

setparams 'Try or Install Ubuntu Server' 
    set gfxpayload=keep
    linux   /casper/vmlinuz auto=true preseed/file=/cdrom/preseed.cfg priority=critical quiet splash noprompt noshell automatic-ubiquity ... ---
    initrd  /casper/initrd

It's interesting that If I add new menu entry to grub.cfg, I see that menu entry during boot, but linux parameters look the same as above, regardless of what I set.

So, it looks like there's a process which runs during ISO packing, which takes grub.cfg as input, and produces artifact which is actually used during boot (or this may happen in very early stage of booting). Anyway, my parameters are gone whatever is happening here.

Is there any way I can achieve my goal?