I'm gonna roll my Chicago Insect Spirits knowledge skill.
Yay! Okay. You're certain that this is a Wasp spirit nest. It fits their modus operandi perfectly. High building, open-air access. All of that. You can confirm that this nest was started after the fire based on that knowledge.. and the lack of soot and such on it. However, you can tell that this stuff on the walls wasn't finished. The whole icky wall thing is prep for a queen, but the prep was never completed.
As to what you know about wasps, they are territorial, venomous and can fly. Unlike their bee cousins, there are only three classes, Soldier, Queen and Nymph. Nests are small, but spread quickly.