Here is the full list of all 14 Hidden Objects: Tranquil Valley achievements.
Successfully completed Time Attack Mode.
Found 60 objects in Time Attack Mode.
Found 50 objects in Time Attack Mode.
Found 40 objects in Time Attack Mode.
Found 30 objects in Time Attack Mode.
Found 20 objects in Time Attack Mode.
Found 10 objects in Time Attack Mode.
Successfully completed Zen Mode.
Found 60 objects in Zen Mode.
Found 50 objects in Zen Mode.
Found 40 objects in Zen Mode.
Found 30 objects in Zen Mode.
Found 20 objects in Zen Mode.
Found 10 objects in Zen Mode.