Agreed. I'm really glad Triss is getting more dialogue in the game. I'm also glad CDPR cares about their game enough that they continue to add stuff like this.I don't think that this is an issue after all. I mean, if people don't want to be with Triss and think that a Geralt that is true to book-lore should be with Yen will never experience that line no matter what. It's not like this line changes anything for Yen fans, just for Triss fans, and those people are usually pretty open to "differing" lore.
But then again I think that this is only mediocre to bad writing on CDPR's side. They are imo better than that.
The issue is the average to below-average quality of CDPR's writing which is often inconsistent with what was already established earlier in this game, in W1/2, in the books, or all of the above. Whether it's poorly worded dialogue, inconsistent characterizations, or flat out contradictions, it all leaves a sour taste.
There is no reason the added dialogue line around amnesia needs to contradict the books in the manner it does. That's just crude, lazy writing. Again, I'm surprised that professional writers who supposedly know the books better than us and who probably read them in their original language produced these lines of dialogue.