https://3ds.guide/ is very detailed and thorough. As long as you carefully read and follow the guide without skipping any steps, you should be fine. Of course, there's always at least a small risk when you do stuff like this, so it might not be worth it for you if the only reason you want to do it is DQ8's soundtrack. Like other people have said, the MIDI music is fine, just not as nice as the orchestra.
There are a lot of other benefits though, such as removing the region locking. So you could import and play DQ games that were never localized, like Theatrhythm Dragon Quest (playable without knowing Japanese, especially if you're already familiar with the menus from Theatrhythm Final Fantasy) and Dragon Quest Monsters: Terry's Wonderland 3D, which got a fan translation.