Here is the full list of all 50 Secret Diaries: Manage a Manor achievements.
Complete levels with at least 1 heart.
Collect roses by completing side objectives.
Find Jerry.
Complete levels with 3 hearts.
Don't serve guests
Checkout guests with 5 hearts.
Watch all in game cutscenes.
Get 'all clean' bonus in 10 levels.
Get 'quick service' bonuses.
Get 'full order' bonuses.
Bake fish in the Kitchen.
Bring fans to the ladies in the Drawing Room.
Test your skills in a fight with Jonathan in the Garden.
Show people how to dance in the Ballroom.
Give out plant books in the Library.
Cook soup.
Play the grand piano.
Water the plants.
Dance with the guests.
Put books back on the shelves.
Finish all levels at the Kitchen location
Finish all levels at the Drawing Room location
Finish all levels at the Garden location
Finish all levels at the Ballroom location
Finish all levels at the Library location
Fully decorate the park.