I think everyone would have preferred the expression to be a smirk or full on smile with the telephone. And after the backlash Hot Toys got when they first revealed the Aldo Raine sculpt, everyone demanding they give him the look he had in the poster, Hot Toy knew what the fans were expecting. So its obvious there were other factors involved that restricted their creativity, besides them just not 'getting' what the movie was about.
Also Landa is a complex character.He has many different faces. When he says bingo, my immediate impression was 'Wow this guy...is crazy' Like he was actually unstable. I don't think Waltz was going for silly or comical, he was trying to convey just how far gone Landa really is. He is so impressed with his own scheme, he's completely giddy
The sinister expression of the figure is very suitable but he could benefit from extra sculpts too. Maybe we could ask for a V2 in the other uniform