i think it doesn't really matter, since haesoo doesn't care about compliments. the reason why the author decided to make taku speak Japanese in that scene, was to symbolize haesoo not being only curious about the actual language Japanese but also body/emotional language, I THINK.
The 'language he doesn't understand' could be interpreted as taku's kind and caring personality. something haesoonis not used to
You are right. Before this i was cynical about Taku's motivation but after he soothed Haesoo in Japanese and he knew haesoo wouldn't know a word but feel him ,i totally believe him now.
Nah, words don't matter in that situation. He could have hum something, it would be the same. It would have the same outcome. I'm ok with that.
If only Haesoo knew what Taku was saying ┗( T﹏T )┛