Area 8
Immediately after you pass through the Checkpoint, look to your left for a path to climb up back towards the Waterfall you passed through. This will get you into the upper section of Area 7, where a bombable wall hides a [GREEN BAUBLE].
To the right of the Hillbilly Still is a path down to a maze of trees. There are [3 BLUE BAUBLES] scattered around inside, as well as the Raccoon Stump (not required for Achievement). There’s also a flammable tree near a Bear down here: if you burn the tree, you can bomb the ground to enter a secret room with Bears and [4 BLUE BAUBLES].
As you approach what I like to call Frogger River, look to the nearest Waterfall, and bomb the very base of it. You can now enter another secret room with a [RED BAUBLE] inside.
Back at Frogger River, activate the two clouds across it if you’re playing Infantile Mode for easy backtracking. Then, jump onto a log on the near side of the river and let it take you towards the cliff edge. From there, you can hop over a couple of stepping stones and a Water Spout to a cliff path that leads over the edge and down towards another [BLUE BAUBLE]. Continue following the path down here until it leads back up the cliff towards a Mushroom and several Petal Throwers. If you fall down here, there’s a Hillbilly Still, and you can climb back up to the Mushroom from there. Once you make it across the Petal Throwers, you’ll reach another Mushroom, a [BLUE BAUBLE], and finally the Log Shop.
The Log Shop has a secret room right by the fireplace, but it’s not required for the Bauble Achievement. (You’ll want it for the Secret Room Achievement though.)
Next to the Log Shop is a bombable wall. Inside this cave are several Toads (kill from afar with Bombs), [2 BLUE BAUBLES] and another bombable wall (in the waterlogged section with one of the blue baubles) that leads to a [GREEN BAUBLE].
Now that you’ve cleared everything on the near side of Frogger River, you can return to the Hillbilly Still at the start of this area. If you drop down carefully, you can reach a ledge underneath that grants you access to a tunnel that a river is running through. If you pass through it carefully, you’ll come to a Mushroom that leads you up to a [YELLOW BAUBLE] and a bombable wall that leads to a secret room filled with Hillbillies. This secret room is a maze, but if you hug the left wall, you should pass through it fairly easily. At the end is a [RED BAUBLE] and an exit that leads to the other side of the river.
After passing through the Hillbilly Secret Room, you can burn the trees and jump a small gap to reach a [BLUE BAUBLE] (this is on the far side of Frogger River, towards the Waterfalls).
There’s another shop before the Checkpoint. Keep it in mind if you need to buy a Key later.
Area 9
The first [BLUE BAUBLE] here is along the series of ledges that lead up to the top of the Waterfalls. You can either use the Mushrooms to get up there and climb, or the Teleporter to get straight to the top and drop down.
There’s a secret room in the first waterfall. If you start from the base of the cliff and use the Mushrooms to jump up, the room is about level with the first ledge that doesn’t have a Mushroom on it (you instead had to jump up some footholds to reach the next Mushroom). Throw a bomb into the aterfall — you’ll hear a little jingle if you opened it up. Edge into the waterfall so that you can use the camera to see where you have to jump, and then go ahead. The shop here sells various “Special Pots”, which are just normal pots you can throw for the items they drop. Doesn’t seem to be worthwhile, though I don’t know if there’s another secret to it.
Just before you reach the Checkpoint, there’s a Chest containing a [PURPLE BAUBLE] hidden behind the last Waterfall. You can either get in here by being high up enough as you cross the logs, or fall down far enough and enter the dark cave network hidden at the bottom of this last Waterfall. Or you could activate the Checkpoint and use the ledges to climb up above the Checkpoint and reach the Chest that way. Use whatever way you wish: just remember you have to get a Key up there too.
Area 10
Almost done. Use the Petal Thrower above the Checkpoint to reach a pillar that carries a [BLUE BAUBLE]. After that, use the next Petal Thrower to reach the walls that surrounded the start of Area 9. If you make your way along the walls towards the Waterfalls and then look left, you’ll see the final [BLUE BAUBLE].
There’s a final Hillbilly Still along the ledges going up past the Checkpoint, but there’s nothing Achievement related up there.
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That should be everything. Hope it helps.