Not to be pedantic but I think the headline is fine.
If you simulated a fire in a building for training purposes and upon activating the fire alarm, it got broadcast to emergency services when it shouldn't, you did accidentally broadcast the fire alarm, simulated or not.
The "accidentally" already implies it was done in error, suggesting it was not an emergency. On the other hand, if it was a real emergency, and just wasn't meant to be publicly broadcasted, I feel like the headline would've looked different.
I guess considering I used to work in Mission Control and participate in these simulations, the language used here is something I notice probably more than others.
The simulation itself was broadcast. The astronauts and the sim team were in Houston. The alarm originated from a computer on the ground in Houston. The comm loops that were heard were from a sim on the ground in Houston. This headline would make more sense if NASA was troubleshooting alarms on ISS and configured things such that those messages would be on a private channel but messed up and the public heard them. In this context the fact that it was a sim is important.
