Hmmm... The Veilguard art book. In it, it was explained that Calpernia and even Imshael(?) could have been party members in the previous iteration of the game.
The Divine sounds like either Vivienne or Cassandra depending on the conversation in Veilguard. I was thinking Lilianna, but Harding said she didn't speak with her much. She was one of the best scouts/spies in the Inquisition. There is not a chance she wouldn't have spoken with "The Nightingale". Side note: The Inquisition should have been a playable faction (If they were retained). I know Harding, Varric, and Charter were a constant, visible reminder, but it would answer your question if we were able to be an official agent from Orlais and not a random field recruit.
You put a lot of minor characters in that list. Omitting Sandal should be criminal. He would have been huge for Harding in this game. He did what she and Valta did alllll the way back in DA:2. Omitting Tallis is practically a war crime. She, Bethany, and Isabella in the same party was "game over" for any enemy. The perfect storm. Her movie was terrible, a terrible waste of a talented actress, but that DLC? Superb.
Some of those characters are/will be in books and comics. Dragon Age movies and TV series need a serious infusion of life. I am looking at Arcane and "swinging at the air" in jealously. Haha Dawn of The Seeker is the only good Dragon Age film, anime at that, and it was short.
There are many more bit players that got cameos in Inquisition, DA2, and Veilguard that I would like to know about as well. Some were in alternate or secret scenes. Others were just mentioned in a passage of a codex entry.
The ending of Veilguard alluded to the big picture and subsequent arcs ballooning outward again, like after DA:2. Other than that, you'll probably never know at the rate we're going. I'll be in a nursing home before the next game drops.
Regards