Is there a way to externally trigger sound playing in the Fantasy Player App (not the online player!), e.g. by Apple Event scripting or preferably special links?
The latter would be better for me, as I could then put the sound links directly into my Obsidian notes 
I’ve been struggling to achieve something like this for years, it’s not possible to my knowledge, I’m afraid, though I’ll be following closely, hoping someone proves me wrong.
For me, keyboard shortcuts would be a viable work-around. They work for one-shots, but not for moods etc. Keyboard shortcuts seems like such a simple, normal, best practice, and the devs here are great, so I’m guessing there’s some hidden complexity or technical limitation that I don’t know about.
That does indeed sound intriguing. As I am using Markdown (in Obsidian) anyway, being able to trigger the sounds/ambiances directly would be amazing!
Could you provide some examples?
I recently released the Syrinscape control plugin for Obsidian. If you’re using Obsidian already, you might want to check it out.
Note that it controls the online player, not the local player. But you can start the web player or the online player locally and hear the sounds. You just don’t have to do all the disc-jockeying during game time. And you don’t have to construct your own soundscapes. Just link to the mood you want from the note that describes the room or encounter.