Hail, Celebrimbor.
Now I have finished reading your story and I loved the end.
I want to congratulate you again on your style, you have managed to keep it old-fashioned and chronicle-like all through the story.
The end is very touching, as well as the fate of Iliandor himself, who decided to die in Cardolan, instead of going to hide n Arthedain. It added much to his characterization. It sounded so true, that Iliandor's book didn't find favor not only with Orodril, but with Amariel as well.
Calime's suicide attempt provided an excellent reason for Amariel to resign. By the way, poor Calime loved a married man, so, even without Telcaran's death her love was doomed anyway.
Where do you get all these names for your story? I loved all of them, Telcaran, Iliandor, or Orodril, for instance.
Your list of rulers is a great asset to the story. And it looks so authentic! I was happy to find the new Queen there. As you asked, I checked all the dates carefully, but I have found no problems- everything fits perfectly now. The only date that I would have changed (shifted slightly earlier) is this one:
"The lands became divided into quarreling fiefdoms until c. 1356, when Taranbar, the son of Halcar, son of Prince Telcaran, was granted the status of Ruling Prince of Cardolan by his liege-lord, Argeleb I, King of Arthedain."
Argeleb claimed Arnor overlordship in 1349, and was not resisted by Cardolan. So it seems reasonable that the appointment of the new ruling Prince should have followed shortly, around 1350-1352. But that is a very minor nitpick. All the rest seems perfect.
Here is the part that interests me greatly:
Orodril’s greatest contribution to Cardolan was the construction of the mighty Hedgewall; an immense structure of thick and thorny brambles and vegetation that ran in an unbroken line from the Nen-I-Sul, near the South Downs, to the river Gwathlo. He ordered it built by his engineers to fence out enemy invaders, whether they be from Angmar or Arthedain, and prevent them from marching on his abode in the south. Yet in later years, well after his death, its walls were breached by the great host of the Witch King in the war of 1409, and much of its length was razed to the ground. The smoke and reek of it was said to have been seen as far away as Fornost Erain.
The Hedgewell is a great idea, but its site seems wrong to me. The line from South Downs to Gwathlo doesn't cover Tyrn Gorthad neither from the invasion from the North-East (Angmar), nor from the North (Arthedain).
Actually I was immediately reminded of this place in LOTR, where the journey from the Barrow-Downs to Bree s described:
They went forward steadily, but they soon saw that the Road was further away than they had imagined. Even without a fog, their sleep at mid-day would have prevented them from reaching it until after nightfall on the day before. The dark line they had seen was not a line of trees but a line of bushes growing on the edge of a deep dike with a steep wall on the further side. Tom said that it had once been the boundary of a kingdom, but a very long lime ago. He seemed to remember something sad about it, and would not say much.
They climbed down and out of the dike and through a gap in the wall, and then Tom turned due north, for they had been bearing somewhat to the west. The land was now open and fairly level, and they quickened their pace, but the sun was already sinking low when at last they saw a line of tall trees ahead, and they knew that they had come back to the Road after many unexpected adventures.
So here is the wall of Cardolan, lying parallel to the east-west road at a distance from it. It clearly protected Cardolan from the North and North-West - both from Angmar and Arthedain. I Believe, you should "incorporate" this canon part of the wall into Orodril's Hedgewell, making it practically encircle Cardolan West - Eas, from the Old Forest to the South Downs, and from there South to Gwathlo.
I also checked the Hedge of Buckland. It is written that it was made by hobbits. But, perhaps they only renewed the older structure - another, western, part of the Wall of Cardolan?
All this is very exciting.
By the way, do you remember our talk about the maps of Rhudaur? I have found some on the net, have a look:
http://hobbitale.iespana.es/mapas/rhudaur.jpghttp://www.angelfire.lycos.com/doc/images/rloadblock.jpghttp://formenos.iespana.es/formenos/runas/tierra_m/mapas/rhudaur.jpgDo they correspond with your story? I have found Cameth Brin, but nothing else.
Is Carn Dum a 'city' in the traditional sense of the word? I thought that Carn Dum referred to the actual tower, and/or the network of caves and caverns in the mnts. Perhaps it is both. In any case, yes, they were certainly once the home of a dwarven colony. I can't recall right now why they were abandoned, though.
I checked again, and found that in Tolkien's own writings the term "city" was not used. Neither was "fortress". Nor there is anything about dwarves and caverns. It is all conjecture (sigh).
But I still wonder how much the Witch King would make himself visible to his subjects.
. He will not make motivational speeches from atop his tower, for sure!

I don't think he will be drinking beer in the taverns of Carn-Dum city either. He will be living in his castle, seen by selected few, or leading his host to battle, mantled, helmeted and masked. Some public appearences are inevitable for a mortal king. Sauron was not trying to appear human, but the Witch-king was.
And how he can make himself visible, if at all, is a very difficult question, it can be discussed for days on end. I have some ideas... but canon tells us nothing.
Thank you again, Celebrimbor, for posting your story and bringing it to the end so brilliantly.
Gordis