Complain about "Rooftop Prince"

The protagonist is the Crown Prince who traveled to 2012 with his three subordinates for some reason more than 300 years ago. Let's not complain about the official uniforms that look like the Ming Dynasty in China. In the third episode, there was a scene where the heroine teaches the male protagonist Korean. Damn, wasn't the writing on the Korean Peninsula invented in 1446? . . Damn, the male protagonist lived in an era when Korean was invented for more than 200 years. What a bummer. Although Korean was not used much in ancient times and Chinese characters were not as popular as Chinese characters. However, the male protagonist, as the crown prince, does not even know Korean. Damn, what a bummer. . . . . .