Here is the full list of all 29 Scarlet Maiden achievements.
Completer the quest ‘It’s a Strap’
Slay 200 enemies in one run
Complete the quest ‘Green Delight’
Level Roman to level 5
Level Faelina to level 5
Complete the quest ‘Magic Flute’
Earned after 10th run
Complete the quest ‘Masquerade’
Level up to level 50
Defeat Queen Lily
Gain 100000 sin total
Slay 100 enemies in one run
Find 50 items in one run
Defeat the Grand Archivist
Gain 15000 sin in one run
Complete the quest ‘Steamy Contraptions’
Defeat the Earth Mother
Level up to level 10
Level Bruce to level 5
Find 20 items in one run