It depends what the "customer" wants.
As you have discovered there are multiple ways to do it.
Digi Outputs don't sink much current so you could overload. It's 1 panel output is a little more.
I'd generally use a PE48 with plugon relay card if I know I need to do stuff like this.
The recommended impedance on the loudspeaker output is minimum to stop a short, if higher it will just be harder to drive so quiet.
Use an expander and it's loudspeaker output if you want remote speakers instead of a mimic sounder.
I'd say with it wired NO it was on mimic before.