Here is the full list of all 27 Shy Dogs Hidden Orchestra achievements.
You found all the dogs!
You found absolutely everything!
You completed the level 06
You found the level 6 secret dog
You completed the level 05
You found the level 5 secret dog
You found the level 4 secret dog
You completed the level 04
You found the level 3 secret dog
You completed the level 03
You found the level 2 secret dog
You completed the level 02
You found the level 7 secret dog
You completed the level 07
You found the level 8 secret dog
You completed the level 08
You found the level 9 secret dog
You completed the level 09
You completed the level 10
You found the level 10 secret dog
You found the level 1 secret dog
You completed the level 01
You solved your first mistery
You found your first hint piece
You found your first dog at a level
You discovered all dogs in main menu
You found a dog at the main menu