Logotyrapy

I am guessing that you have to wait till the following reset after completing Time to Process to get this followup quest. I completed the questline a week after its release when the tabard source was announced and have not received the mail to start this final quest yet.

Edit: also confirming I did get the quest item in the mail with the following weekly reset!

The entrance is at /way 59.78, 63.79

Some lore from items found on this chain quests:

[item=210255], found while doing Infiltrating the Nighthold:

Day 1: A mysterious disc of Titan origin was found in one of the canals today. There's no telling how long it has been there.
The Grand Magistrix herself charged me with gathering researchers to unlock its secrets!

Day 8: When Grand Magistrix Elisande is able, she checks in to see how our research is progressing.
We've catalogued the disc's properties. but so far have found no way to access the data it must contain.

Day 17: Magistrix Elisande has requested more frequent updates on the status of the disc.
We've made little progress. unfortunately, and she seems to be growing impatient.

Day 29: One of my more promising researchers, Runas, found the disc seems to react to a certain spell.
When I cast it upon the disc, it produces a feeling in my mind, as though it is revealing secrets to me.
But I can make no sense of the flashes of
thought it creates.

Day 36: I showed Magistrix Elisande the spell, and she seems to have more success at understanding fragments of the disc's knowledge.
Perhaps with practice, I will be able to comprehend these impressions as well.

Day 43: With repeated daily effort, I've been able to grasp larger and clearer fragments of the disc's knowledge.
Elisande's proficiency has grown even more quickly. She says it belonged to the Titan keeper Tyr, storing all of his knowledge.

Day 52: Elisande and I have learned a great deal from the disc. Our knowledge of the world pales before the brilliance of the Titans!
They see order in many patterns we had assumed were purely chaotic. It's impossible to predict how our continued study could impact the shal'dorei.

[item=210321], found while doing Logotyrapy:

Honoring Tyr's Legacy

When I determined that reforging the Tyr's Guard was the best way I could honor the legacy of Tyr, I decided to record notes on events and individuals so that future members of the Tyr's Guard could look to our history for guidance and inspiration.

Koranos

Koranos went with me to Tyr's tomb to witness his final memories, and since then, has been utterly dedicated to the cause of Tyr. This Titan watcher has a level of determination I've never seen before!

In addition to accompanying me on my journeys through the isles to find our recruits, Koranos also did most of the work to clear out Tyr's Rest. Without his help, I don't think I could have re-established the order.

Tyr's Rest

When Koranos and I found Tyr's Rest, it was a largely empty hall, close to Tyrhold, full of discarded Titan relics and remains. We cleaned out most of that, and I sent a letter to the Silver Hand, asking if they had any extra supplies. They sent what they could spare, and now Tyr's Rest is our headquarters. The result was a strong foundation for building the Tyr's Guard.

Right now, there aren't many of us, so a headquarters isn't too important. But soon, I suspect paladins from all over Azeroth will want to see what we're doing, and possibly join our ranks.

Exemplar of Sacrifice: Nolaki

I came upon Nolaki on the road from Wingrest Embassy. She and her brother were trying to protect a pair of dragonkin from a great Djaradin champion.

They appeared to be quite outmatched, but Nolaki was deeply committed to protecting her brother - a strong warrior in his own right - with no thought for her own safety, and no fear.

I knew she belonged in the Tyr's Guard as the Exemplar of Sacrifice. Though if Koranos and I hadn't come along at just that time, that likely would have been her last heroic act.

Exemplar of Order: Talthis

Talthis is simply unusual in how he values order. Koranos and I found him at the Flashfrost Assault, where the primalists attacked the Ruby Life Pools.

He was surrounded by heaps of stone and gravel from defeated elementals. More kept coming, and he kept fighting them, tirelessly. All the while, shouting about how disorder would not carry the day.

Koranos and I joined him, and when the dust - and gravel - settled, I told him how the Tyr's Guard needed an Exemplar of Order in service to Tyr. He joined us without hesitation.

Exemplar of Compassion: Valunei

I saw Valunei when we were on our way from Valdrakken to Tyrhold. She had stopped to help an injured drakonid, who said he was a veteran of the rebellion against the Aspects. Contemptible!

But not only did Valunei heal him, as we were walking up, I saw her hand him a pouch of gold. She refused to tell me how much was in it. But she helped that drakonid - who had been injured fighting against good and order - without stopping just at his physical injuries.

Seeing that, I knew she was the right paladin to serve as Tyr's Exemplar of Compassion.

Exemplar of Justice: Hadwin

We met Hadwin in the Ohn'ahran Plains, as we heard loud noises off the main road. Following the sound, we came upon Hadwin and a centaur - Bolor, I think, her name was - fighting gorlocs.

The gorlocs had killed her hound companion, and Hadwin, having heard her story, accompanied her to bring justice to the gorlocs. Bolor had wanted to kill every gorloc in the camp, but Hadwin insisted, they would only fight the gorloc chieftain, and those gorlocs which stood in their way.

Seeing his commitment to make things right, and his aversion to vengeance, I knew he would be our Exemplar of Justice.