Pardon me for jumping in. This thread caught my eye because I have a Project that already incorporates parts of this.
My application is common - my wife or I will set down our phone somewhere in the house and then we can't find it. "Call the phone and listen for the ring!" That doesn't help when the phone is on DND, silent, or vibrate.
So my Project monitors SMS for inbound texts from specific numbers, hers or mine, and that begin with an exclamation. On receipt of a command like !hey, the tasks disable DND if it's on, set all volume levels to high, and then Beep tasks loop with a brief but annoying pattern. This also returns back to me an SMS that confirms the phone's previous and new volume settings, so that I know if it actually made changes. I'm going to add %BATTERY in the return message, as well as the current location ... in case we can't hear the phone even with the volume up because it's outside somewhere.
It seems the OP here wants to do something similar, but adding tasks to:
1) disable bluetooth, or perhaps to play through speaker when a headset is plugged in.
2) play a ringtone or audio media with a pre-defined pattern ... not my Beeps.
I might be wrong, but I'm thinking the Silence app is simply toggling the phone's DND just like we can with Tasker. So you should be able to add that into your own Project.
In summary, I think the tools are here to meet this challenge. I dunno about stopping/continuing current audio or otherwise overriding settings from another app. That might require Intents.
I hope some of this is helpful as a confirmation that yeah, you can do that.
I'd publish my Project but I can't at the moment because I have too many hard-coded details in the actions. But I plan to publish after I abstract that stuff outside of the Project, and add actions that read in the data for the current device.