Tbh I've never said I dislike Titania more or less than Saphira, they're both horrible human beings on the same level as Sirius, Solaris (and their pokemon) and Lin (she kills Taka in Reshiram route right?). But you're correct about their screen time: as a matter of fact, I really disliked Vanilla at first because of her arrogance, but that aspect of her personality seems to have been toned down to the point that I prefer she keeps her pride as a trainer (and as a person who hates Saphira as everyone should do) instead of getting help from the person who has been insulting her since their first meeting.
In my opinion, at this point it would make more sense if that Unown showed up and told Vanilla the "correct" strategy to win (did I really figured it out? I don't remember).