Shortcuts and automations with home app

I'm trying to setup an automation in the home app so that every time my security camera detects motion it informs my Apple TV (running as home hub) to play a file from iTunes (a recording of a trespass notice I made myself) out of an airport express I have on same network (and in my 'home') into an audio amplifier which then plays out of a speaker.

I HAVE had this working, but it doesn't work every time.

I feel it's possibly because the camera is a netatmo and has it's own app as well as going through 'home'.

The netatmo app is a bit rubbish, hangs, says cameras aren't online, even though if I then go into 'home' I can see them perfectly.

I also think it could be because the automation is possibly trying to download the audio file or stream the audio file on demand, maybe....

Is there a way to have the trespass .wav stored on my Apple TV locally? I feel like this would solve the inconsistency.

I'd also like to add a shortcut for playing this sound out of the airport express attached to my home so I can trigger it when away from home network if for some reason the home automation has failed.

Any help would be great. Like I said, I HAVE had it working, but it seems like it works for a bit and then just can't be bothered. It seems like there's a conflict somewhere.

Thanks