That is a shame about the bugged quest, hopefully they patch it up. The developers did say that Triss would be a very important character and that one of the big choices would be deciding between her and Yen, heck they showed quite a bit of Triss in the trailers, and in cosplays etc, so i don't know what happened (if some of her content was cut out), but yeah i was also worried about Yen being in the spotlight, although i didn't worry after seeing the trailers where it genuine looked like the developers made Triss a major character (like the previous games).
On a side note, Dijkstra is awesome, didn't really like him at first but he quickly grew on me.
She is a major character, she is literally the only LI that carries over from game to game, although I prefer her more in w2 and w3. Still gave her Alvin, but let's be honest, romance in w1 amounted to collecting cards.
And the choice over Yen or her is still there, they just forgot/couldn't/decided not to add the consequences.
As I suggested in another topic, it is my opinion that the original plan was to have Geralt meet her in Novigrad, have a closure of sorts and for her to depart to Kovir forever, so players were "free" to able to fully engage Yennefer. Think about it, almost every other scene after that is designed with those events in mind.
Sure she comes back because Yennefer asked her to. It even states so in the lorebook. After all even Geralt saying that she loved her and her agreeing to go to KM to meet him it's really not that important for Triss, he is just what, the life of her life? No biggie. Or perhaps, she comes back only at Yen's behest because we are in a world that was created with the idea of them parting for good. Which option makes the most sense?
To add salt to the wound, every other character that comes to help, comes because Geralt asked them to. Yen only rallies the woman whom she got dumped for. Wait, again in this state of the world she didn't get dumped. After all she kissed him when Ciri came back and Triss silently watched with sadness in her eyes, again because they had decided to part for good and she had to accept that.
List continues but you get the point.
I don't even think she was supposed to be in the ship in the end, she had no dialogue options and no quests associated with her. There was even no banter with her and the other characters.
The biggest argument is this though: They have done a wonderful job in every other part of the game, down to the last detail. An oversight of this magnitude can only be explained because it was, at some point, by design.