Instead of figuring it out, mount the install.wim, run your command without the /quiet /norestart targeting the mounted wim, and save/unmount the wim, now it's pre-enabled. I have seen crappy homebrewers doing what you want, it took ages to complete and looked very amatueristic to see all kinds of cmd windows during setupcomplete.
I am still lost on NetFX updates for 1809... WHDownloader shows these: - Windows10.0-KB4480056-x64 - Windows10.0-KB4502559-x64 But not this one - Windows10.0-KB4502564-x64 Do I need all 3?
KB4480056 & KB4502559 are only for NET 3.5 & 4.7.2 but KB4480056 has been replaced by KB4499405 which is for NET 3.5, 4.7.2 & 4.8. KB4502564 is only for NET 3.5 & 4.8 so all depend of which NET 4.X do you have installed.