Can unity Check if certain fmod event is playing?

Unity
7

how should i reference the specific Jetpack event doing so in the script
with no emitter ?

How are you actually playing your jetpack event? If by creating and playing an event instance in a script, then you can use the code snippet posted in my first answer in the same script.

where should i put the “isPlaying” method script so i could call it anywhere on every event instance ?

There are different ways to go about this, you could make the method static so you can access it everywhere:

public class FmodExtensions
{    
    public static bool IsPlaying(FMOD.Studio.EventInstance instance)
    {
        FMOD.Studio.PLAYBACK_STATE state;
        instance.getPlaybackState(out state);
        return state != FMOD.Studio.PLAYBACK_STATE.STOPPED;
    }
}

Then just call FmodExtensions.IsPlaying(yourInstance) from where you want.