You don't need to track anybody down.
I found an iPhone 5 on the beach, after contacting the provider to try and track the SIM card to someone. I discovered the iPhone I found was not the iPhone that matched the SIM card. I found an obviously stolen phone. I found the owner to the SIM card and she said it was not her phone (grey) and hers (gold) was stolen at a restaurant a week earlier. I took the phone to the police station and picked it up after the mandatory 30 day waiting period. I then took it to the Apple Store with the paperwork from the police that said the phone was legally mine and it was unlocked and wiped for me by the employees.
I'm having issues wrapping my head around why Apple won't just go and make this policy. If you can prove the device is legally yours and you have checked for the previous owner, what is the issue? The phone was legally mine and I could prove it so they had no real problem unlocking it. I can track my watch/computer anywhere on the planet AND Apple has all my contact info, then why don't they contact previous owners and tell them their device has been located? I would EXPECT that if my MacBook found its way to the store without me and I had reported it stolen the employees would take measures to get it back to me. Hummm.....
On the other hand Apple could be using this to maintain higher prices and sell more products given it is so easy to brick them by locking iCloud. Good luck with the watch.