Thanks for the try. My first stroke of genius was to add a counter. For every of this instance playing add one to counter. If counter is above 1 then stop sound. Sounded logical. But it stops all sounds, not just the offending one.
The same would apply to your idea. Once you throw in that stop sound, it stops all certain sounds. Not just one, or the most recent one.
I think my ultimate solution lies in some of the timeline and cooldown plugins for C2 that I'm checking out now. Essentially adding a cooldown to a sound so it can't play until the cooldown ends. Still a bit hacky.
I'm an audio engineer by trade for the video game industry and I'm kinda spoiled on audio middleware like wwise and fmod that allow you to create a basic rule and priority system for audio.
I'll keep trying stuff out though, thanks!