I don't say this with ill intent and I hope that's clear, I'm bisexual myself and I like seeing bisexual characters on screen. Unfortunately I don't know if that's what I'd consider Shadowheart, although it's easy for me to HC her as such.
I don't sense any ill intent at all, and I see the point and agree that bisexuality can get lost in the mix when you have playersexual mechanics.
It's a matter where interpretations of the character can differ greatly. Her interest in Karlach and past relationship with Nocturne is solidified through twittercanon more than in-game canon, so it depends on what emphasis you put on that.
But as Larian's developers also have said so eloquently "The characters in Baldur's Gate belong to everyone now." And that means that headcanons and fancanons are valid as well, if the lesbian and bisexual players have taken Shadowheart to their heart, then she belongs to them just as much. And Larian's writers, her VA and the entire team around developing her as a character made her believable and enjoyable to those players.
