I'm trying to get a gold laurel wreath in Pandora's Labyrinth of Deceit, but I don't know where the treasures are!
There is a treasure chest in an early room with a moving wall. It is in plain sight, although a bit tricky to get to because of the moving wall.
In the first room with the Exo Tank, take the jump and land on the raised platform. Get off the tank to trigger a treasure chest. Sticking a landing on the platform while in the Exo Tank can be difficult. One way to make it easier is to jump out of the ride as you're in mid-air about half a second after launching from the ramp; your momentum should carry you onto the platform to grab the treasure, and the Exo Tank will be waiting for you when you drop down.
In the room with bouncy floors there are two intensity gates, level 4 and level 8. The level 4 gate can be found by hugging the right wall. The level 8 gate is near the bottom by a reaper.
In the second room with an Exo Tank, boost on the ramp to land on the raised bit. There's another treasure chest. If you have a hard time getting up on the ledge with the Exo Tank, you can also get up there easily by using the Sky Jump power after landing on the lower part of the platform. Just be sure to get a walking/running start before using the power, because you can't change direction in mid-jump and you need forward momentum to climb onto the ledge.
There's a treasure chest in the room with invisible floors. After reaching the platform with the cannoneer on it, shoot and reveal the invisible floor ahead to find that the path forks; take the left fork first to find a treasure chest, but BEWARE that an Orne appears near the chest on higher Intensities (5.0 or above, if memory serves)!
In the room with the invisible floors, you can keep going past the exit door. Step on the jump panels to go to another treasure chest.
You are probably missing the level 8 intensity gate.
To get the golden wreath, you'll need not only all the treasures, but also the intensity gates. According to this guide, the listed treasures and intensity gate are:
The third room...tempts you with a sometimes accessible treasure chest. If you want it, just be sure to watch the floor and the wall to get your timing right. Falling down hurts.
The next room contains an Exo Tank. You can simply drive it to the other side of the room, but you can also go around and destroy enemies by simply running them over. You can also use the tank's boost ability while climbing up the ramp to get on the floating platform. Get off, and food and a treasure chest will appear.
...a few rooms after that has one that contains trampoline floors. Be sure not to jump off of a platform. If you stick to the right, you'll find a Level 4 intensity Gate.
...Keep on attacking enemies from a distance to ensure safe platforming, and then travel carefully. Next up is another Exo Tank section. Eventually, a ramp will appear. Go up it. If you boost at the very end, you'll land higher up, and will be able to open a treasure chest.
The final trial is a room with invisible walkways. ...At one point, you'll be able to go left instead of forward, and can grab a treasure chest.