I actually had to combine 2 different methods, along with a tweak of my own, to make it work. But it’s not as hard as seems; it’s just a matter of following the steps carefully.
So, creating a bootable Windows installer USB drive becomes a little bit of a problem when you are trying to do it on a Mac. Without going into the details, the problem is caused by a large file that is simply too big for it to be written into the USB drive in a way Windows will be able to read it.
I’ve tried a dozen different ways and apps and only found the combination of these 2 methods to work as intended: