Based on OP's criteria I somewhat agree with his placement with a couple shifting slightly on one of the axis:
Lae'Zel: I think you're pretty spot on with Lawful Neutral (teetering on Lawful Evil). I don't think anyone would deny she's lawful, and she doesn't "quite" go out of her way to be combative/aggressive. However, still will easily resort to it.
Shadowheart: I'd actually say she Lawful Neutral (leaning Good imo). Admittedly, I put a lot of weight in her strict adherence to he Sharran mission given what she gave up before she left. Also the fact that, at least in my few playthroughs, she still keeps most of the details about that to herself. Even when I managed to romance her.
Astarion: Chaotic Neutral. He obviously prioritizes himself and his pleasure above pretty much anything, but even the fact that he continued to feed on animals until he started feeling weak keeps him out of evil for me. I mean he could've been snacking on Tiefling kids.
Wyll: This is the hardest for me to place, but I'd say True Neutral and leaning more Good (maybe some towards Chaotic). He seems to want to help people, but he always goes back to getting credit/glory. So he doesn't come off completely altruistic to me.
Gale: He's Neutral Good (bordering Chaotic). Gale definitely presents as good aligned as he praises the PC anytime something good happens. However he is also willing to try some sketchy stuff to accomplish his goals.
