Glad you found it interesting, when my grandma used to butcher (I think that’s the right english word for it) chicken she always made it from fresh blood and liver, it tasted amazing. When it was a rooster she also added the testicles.
The recipe seems legit, google translate only makes one mistake. You should pour the blood into boiling water with a pinch of salt, not a pinch of blood into hot water. Otherwise that’s how I’d prepare.