I don't believe Triss manipulated Geralt with the main goal of furthering her political career. She definitely wasn't 100% honest with Geralt regarding politics in TW1, but I don't think that is the reason she wanted to be close to him. The way I see it the manipulation done by her is mostly for more personal reasons. She definitely made some bad choices, but I feel it's mostly to pursue a relationship with Geralt. Her withholding information on Yen and Ciri(this is probably just a design decision for TW1, but let's assume it's not) is a shady move regardless of whether she knows Yen is alive or not. She took advantage of an opportunity to be with Geralt, something she wanted but could never achieve without his amnesia.
As far as the rose theory, I find it interesting and definitely plausible, it is possible that Triss feared losing Geralt and clung on to any hope of keeping him, but again I don't think she did it for any other reason then her love(or as some see it,obsession) for Geralt and the desire of not losing him. As far as the politics in TW2 goes, I believe that the Lodge kept her in the dark about most things and don't think she purposely outplayed Philippa or Sile to make her political position better. Both her and the Lodge were outplayed by Letho and Nilfgaard.
In TW3, I think she is honest. Triss undeniably has political ambitions, but I don't think she would put them before Geralt(in the books, maybe, but based on her game interpretation it is very unlikely), so the theory that she is plotting with Dijkstra and Tancred to manipulate Geralt isn't something I believe. Dijkstra and Tancred plotting I could see, maybe trying to use Triss and her close relationship with Geralt to assure his help, but I just don't see Triss doing it in collaboration with them.
In my opinion Triss, while manipulative, isn't really a master of manipulation or someone who's only been using Geralt throughout the games to secure her political gain. I think she genuinely loves Geralt and most of her manipulation is done with the goal of having him in her life. She is not an angel, and has definitely done some morally questionable stuff, but I think she is a good person regardless, especially when you look at her in context of the Witcher world, inhibited by far more devious people.