I mean, just because alignment isn't a defined mechanic doesn't mean you can't define good or evil characters. I think Kanisatha is a bit too morally rigid regarding Gale and Wyll in particular (actually, I cant quite recall his stance on Gale) but otherwise, Shadowheart is evil by dint of being a Shar worshipper (just because we haven't seen her do anything evil doesn't mean the priestess of the very evil goddess isn't evil. She's recognised enough that Shar deemed her worthy of granting her spells, which should tell you something). Astarion is obviously evil and would be if left to his own devices. Same with Lae'zel. And even though I think he's too hard on Wyll, I don't think you can put Wyll any closer to good than neutral at this point, but he wants to be good, which to me counts for something. Gale meanwhile is the one closest to being uncomplicatedly good, and I still get the distinct impression he's manipulating us at least somewhat.