We Happy Few

It helps to use Theotar as your soulbind for this as well since he gives a little boost to guest happiness during the Ember Court.

I achieved this without any special effort the first time I did the The Countess Ember Court Strategy (from the Ember Court Strategy Guide - Increasing Happiness with Every Guest, that is with [npc=168450], [npc=171847], [npc=171839]&[npc=171841] and [npc=165269].

Refreshments: Tubbin's Tea Party
Entertainment: Atoning Rituals
Decoration: Mortal Reminders
Security: Stoneborn Reserves

... and Champion's Anima Pod in the [item=181441].

The following day after I completed this achievement I realized I could've done it together with Master of Ceremonies. My comment is a simplified version of another users comment on that achievements page written by Xirev. If you want the original guide instead then click the link to that achievement and upvote him too.

Basically you get these RSVP'S:

Sika (Clean),
Droman Aliothe (Relaxing)
Polemarch Adrestes (Clean, Formal)
The Countess (Decadent, Relaxing, Formal).

Grab these amenities:

Tubbin's Tea Party
Traditional
Glimpse of the Wild
Stoneborn Reserves

Purchase 15-25 [item=180248] so you don't need to stress too much.

Start the ember court scenario and do these events:

#1 A Quiet Moment: Sit in the chair located close to where the teapot event starts and just click 1, 2, 3 and you are done. You can do this during the preparation timer.
#2 Tea Time: Click a pot and start serving tea. There are two pots on the table. (You can cancel the teapot and it completes the event but I needed the reputation from happy guests so I served all the tea)
#3 Traditional Candles: Click on 10 red candles around the entire court area.
#4 Roaring Fires: This one autocompletes when the ember court timer runs out so feel free to ignore it. I was at 9/10 events by the end and this did it for me.
#5 Animal Rescue: Click on Niya and put the small gormlings digging under the ground back in the boxes (Just wait for the gormlings to come up again if they are underground) and put the fishes back in the big water bubble by clicking on the thing on the ground by the bubble.
#6 Ride on the Wild Side: Ride the big gormling back into his cage (make sure to eat npcs and boxes on the way or you fail) Watch this video beforehand for a safe path to take: https://www.youtube.com/watch?v=kmgH9AIyryU

Along with that you need some random events and also the party crashers that will show up during the scenario. Remember the slime downstairs drops an item you can turn in counting as one event too.