Hi, Chiel! Thank you for the hard work!
The OST sounds good! It really sounds like a battle. Is this an OST you commissioned from them?
Regarding MBTI, it is okay to be skeptical. What I'm trying to advocate about the test is that it is not as bullshit as horoscope (sorry for people who believe in it), that's all. I really don't want people to think they are in the same realm XD It is really based on psychology theory (though some would think it is a pseudoscience due to the low validity and reliability). It takes your answers and creates a percentage from them, then gives you some prediction based on it. Horoscope tells your personality from your birth month. How is that logical? The way birthdays can influence your personality is from the context of time, that's all.
However, I don't recommend people to define themselves with MBTI 100% either. Personality is complex. Categorizing a person with these letters will get them to be stereotyped, and that's not fun I guess. I would say the most reliable of this test is the introvert/extrovert category. I personally am proud to be 75% introvert. I'M AN INTROVERT AND I'M PROUD.
(If people don't know, introverts mean people who get their social battery charged by being alone, while extroverts mean people who get their social battery charged by being with people. Not about being shy or being outgoing like that. These get misunderstood a LOT so I put it here just in case.)
Okay, despite my nerdy chatters, my main reason to recommend you this is because it is a good way to deepen characterization and character comprehension, honest XD It's fun to hear that it's accurate for the boys tho, because sometimes it's not!
Edit: Chiel, do you mind if I make fan edit from your files? It will include tampering with your demo ofc, I don't know if you mind it or not, so I will ask for permission first.