I ran into something similar as a Dutch person trying to buy a car from Germany. The initial plan was to drive the car back from Germany, but to do this I had to get an export license plate. This can only be done in the municipality where the car was sold, and they told me I was lucky because I could get an appointment quite quick, which was a month and a half from now. I would also have to bring the car to the Straßenverkehrsamt. How I would have gotten the car there was also a mystery to me, as I did not have a license plate and to get a license plate I would have to bring the car there. If I did somehow manage to do that though, I would have to get a physical license plate made and then get temporary insurance. Not a single German insurance company said they could insure the temporary license plate, as I was not already an existing customers of theirs. I ended up just renting a car transporter and bringing it home that way.
The process of getting a license plate once home was actually a breeze. I used the website of the Dutch Vehicle Authority to make an appointment (for the following day at 2pm) and they gave me a temporary license plate. I simply had to write this on a piece of cardboard and put it where the license plate would go. Called the cheapest insurance company to get temporary insurance, which was no problem, and simply drove the car to get it inspected.
To be honest though as a foreigner living in The Netherlands who doesn't speak a word of Dutch past "lekker", your bureaucracy and general services are probably one of the best in the world. Even your weird medical system is amazing when you actually need help - which I did and got top tier care, extremely fast. The Netherlands should just export their whole system to all of Europe, including the way information is documented in English in every official website.
On top you got a culture of being on time, which is prevalent everywhere, and you wait for stuff very seldomly, and only for a few minutes. Waiting for anything was one of my biggest irks in my home country, the fact that I can make an appointment, be there 5mins early, and get the service, blows my mind.
I doubt many foreign governments would agree that all legal matters should be documented not only in the language of that country but English as well.
While some countries provide a non-binding translation for many things, someone could set the precedent in court that the English translation if relied on by enough people is somewhat binding or similar - Result would be two slightly different (mis-)understandings about the law, due process and bureaucracy from official sources. That could be have unforseen consequences.
Just because many people happen to speak English doesn't mean everyone has to.
There are red license plates for this exact case. Car dealerships generally have them to allow for test drives and bureaucracy drives.
If you buy a car (which is currently unregistered) from a private person that doesn't have those, you just did something that the bureaucracy didn't foresee and at that point, the best course of action is to avoid as much of it as possible.
At this point I have no hope that any of this will getter unless the german state collapses completely.
The process of getting a license plate once home was actually a breeze. I used the website of the Dutch Vehicle Authority to make an appointment (for the following day at 2pm) and they gave me a temporary license plate. I simply had to write this on a piece of cardboard and put it where the license plate would go. Called the cheapest insurance company to get temporary insurance, which was no problem, and simply drove the car to get it inspected.