The best LGBTQ character award is chosen by public vote. So the success of Baldur's Gate and popularity of Shadowheart as a romance option probably played a big part. She probably wouldn't have gotten the award if she was a lesser known character from an indie studio. There is an Authentic Representation category, awarded by a panel, which focuses more on the authentic LGBTQ experience.
Ah, my bad then. I still think she shouldn't have been nominated (maybe that was also a public vote?) but if she won by public vote that makes sense. She is a very popular character.
