https://www.thewrap.com/the-promised-land-review-mads-mikkelsen/
Apparently it's complete historical fiction and Kahlen was a superdick who probably never even met Schinkel who was also not the maniac the movie portrays him as.
De Schinkel
Nah, only in the movie. https://da.m.wikipedia.org/wiki/Frederich_Schinkel