Very sorry to hear that. That's just awful.
I live in a very old very large and well sound dampened apartment and i have fairly loud neighbors above me and a family with a frequently screaming child to the right of me and none of us can hear each other unless we're in the driveway. I've played audio files for all my neighbors at ear splitting volumes of probably the worst case scenario of how loud an amazon could be (Literlaly not a single amazon i've met has had issues with loudness nor do any of the amazon owners i talk to have loud amazons other than the morning or evening flock call which won't be a big deal. THough i know it's not uncommon to find frequently loud amazons.) and none of them said they could hear anything. This is a concern of mine though though I'm only going to adopt an amazon that hasn't had a history of frequent loudness or screaming behaviors. I already have a contingency plan lined up to build homemade acoustic panels for the ceiling in case I end up with a loud one. I've talked to everybody in my unit and told them my plan to get a bird and told them about a worst case scenario, none of them are worried and pretty much all of them are excited that i'm going to get a parrot and keep asking me when I'm bringing one home. THey all said if loudness issues arise they're going to work with me and not go to the landlord but this is a fear of mine.
I'm so sorry to hear about percy and I hope he's happy at his new home and makes the transition well.