I think I found another bug of CsoundUnity.
Did you remember the relative path you told me before?, the "AudioPath" channel in Csonund stand for Assets/Audio and use that channel to store in a String variable so that you don't have to type the directory from the root in your computer? Although it works in Unity, but when you build the project if you use "AudioPath" %s, the audio processed by CsoundUnity won't be played anymore. The I switched back to using the directory from the root "/user/.../UnityProject/Assets...", and build the project, the audio will play.
Is that also happens to you? Maybe you can try it out sometime.
Sorry for so many questions, haha, but I really think CsoundUnity will help a lot of game audio developers.