I'm not for changing the title of the thread, because as it is currently worded, it makes it clear that the poles of opinion about Triss's character are exaggerated in order to suggest that reality lies somewhere in between.
Real-world amnesia doesn't make a convincing context for analyzing Geralt's and Triss's interactions. Geralt never had any condition approximating real-world amnesia, retrograde, dissociative, or any other. To be more flippant about it than the writers deserve, he had Hollywood amnesia. It is a valid literary device, but it is clearly a device. It also means real-world therapies for amnesia do not apply. Only his condition as it is described by an authoritative narrator is true in the world of the games, and proposed therapies are to be evaluated by evidence for them in that same world.
We find five (depending on how you keep count) attempts to restore Geralt's memory. In the first Witcher, Triss advises him to create a new stable personality. She gives a reason for this that is not worse than plausible in context: she does not want to impose on him her ideas of who he should be. Comparing this advice to real-world therapy is not useful, because it is not advice for a real-world condition. Furthermore, it is made in order to encourage player decision-making in gameplay.
The second is triggered by the Crinfrid Reavers' mention of the raven-haired sorceress "Conifer, or some such". It results in Geralt having enough recollection of Yennefer to ask Triss to recount their relationship. We don't know how truthful Triss is when she does so; Dandelion's description of her recounting their "toxic" relationship is not that of the world's most reliable narrator, but it suggests Triss might have colored the story.
The third is the Rose of Remembrance. Triss offers to use the Rose to restore Geralt's memory. We later see the Rose used in a different way that suggests it may have had a different purpose. What we don't know is whether that was its only magical use, or whether it could be used as Triss described. An ingredient of that power might plausibly have different powers in a different application.
There's also the Elven Baths. The fact that Geralt receives a bonus of magic resistance if he abstains is often cited as evidence that Triss was using magic on him. It's not so clear-cut. The Elven Baths are a magical place. It could just as well be the magic of the place that influenced Geralt and Triss to make love there, or that Geralt chose to resist.
The method that was completely successful, of course, was Geralt's participation in the Eternal Battle. Triss was in no position to suggest this at that point in the Witcher 2 narrative.
Even taken together, none of this evidence sustains convicting Triss of trying to manipulate Geralt by a "reasonable doubt" standard. She did not violate any principles of psychology valid in her world. She did not volunteer anything about Yennefer, but did not withhold her knowledge when Geralt asked her to tell him. As to what she said, we have only hearsay, from a witness with a well-known tendency to embellish. The often-cited evidences of manipulation, the Rose of Remembrance and the Elven Baths, are ambiguous. In all, the charge against Triss of trying to alienate Geralt's affection has to result in a "Scots verdict": "Not Proven".