It really depends on how it was done, I suppose. I haven't done the Cassandra romance, so I can't comment. However, I am familiar with the Anders dialogue and how it plays out in the appropriate scene with male Hawke. Switching that particular scene just doesn't fit in the bedroom context as it plays out in DA2. There is no other dialogue to supplement the fact that he is reminiscing about his now-dead former lover, to then segue into making a move on Hawke. The difference is in the fact that the Cassandra scene was written that way, but the Anders one was not.
You could say the same about any sort of pre- or post-sex dialogue that is somewhat troublesome in an emotional way. I will even say this about the Dorian dialogue, although that largely depends on how you RP your Inquisitor. Up until that point, Dorian is so confident but then... he's just not. Before Dorian explains the issue, I don't think that an initial first thought from the Inquisitor of, "Did we make a mistake?" would be unwarranted. Dorian may think that he was hiding what he wanted, but I think that he does send some clear signals in the lead up to sex, particularly during and after the amulet quest. When he says those initial lines, my Inquisitor is confused because he thought he understood what Dorian wanted, and also thought that Dorian understood what he wanted.
If done well, such conversations can add depth to a game romance. But again, the Anders romance was not written that way, so sticking in a scene that has no purpose in the moment seems an unfortunate choice. However, I like that the modder thought to include that for the female Hawke at all. For all I know, there may be some limitations to editing the original scene as it happens in Act 1, so it might be that or nothing.