first , sorry for my bad english.
I found 6 collectibles by myself
except yours here is what I found:
-Landing at the ore offloading facility
When you arrive on scaffolding with many points grapple .After you grab the 3rd , double jump at the right to find a collectible.
when you are on rafts then backtrack to the third rafts to get a collectible.
-The abandoned mine
when you are attacked by a lot of little spiders , on the right of a mana mask , jump on the alcove to find a collectible.
-City of the dead
-The top of the world
After an arena when you fight against 2 sorcerers. Take the grap point and before crossing the wooden bridge to go "Where god rest" turn at the right where a wall is broken to find a new collectible
-The Rainforest City
-The draw bridge
when the drawbridge appears with fire boulders , on the bridge jump right hovering toward a platform with a new collectible.
Toward the mountain of time
after beat the flamethrower , go back at the left near a red mask to get a collectible.