Here is the full list of all 12 Harmonium achievements.
Buddy up someone for the first time
Finish the game
Buddy a traveler from far away
Fully upgrade your house
Complete a rare event
Unlock every buddies except one
Unlock the last buddy
Finish the game in less than \o/ weeks
Finish the game on the very last event
Gather more than 5000 resources in a single week
Reach 50 in every stats at the same time
Have the max possible power, but none used