Carissa vaguely suspects that you can't solve sex in the same way you can't solve sword fighting, the best tactics depend too much on the adversary's tactics. Obviously some people are much better than others at swordfighting, and at sex, but it's not something like logic where there's a correct answer with properties no other answer has; people have incredible sex with succubi or whatever but they don't all describe the sex being incredible in the same way, the way that fleshshaping is in fact mostly described in the same way. If she tries to think back on all of the best sex she's ever had it has notably little to do with technique, rather than 'I just wanted it really badly that day' or 'I'd never tried that before and that was a perfect way for it to go for the first time'.
...this seems like not the time to argue this point. Plausibly there Is no good time to argue that point but right now she is uniquely incapacitated in arguing it, and in fact should probably focus on demonstrating competence at the object-level problem, which, as described, doesn't sound that impossible, even if in Golarion a guy will normally just tell you to slow down or whatever. ...probably if having sex with Keltham is an important ingredient of a plan to seduce him to Lawful Evil, then she can justify the expense of having someone mindread him and telepathically give her cues - and probably she is overthinking this and can just imagine he is saying 'slow down' at the point where she'd expect a guy to say that, and see if that suffices, and involve expensive and risky intimate surveillance arrangements only if that fails. Yeah. There's a good plan.