This is a bit off topic but I fear Karlach won't fit in a good aligned party. It's been speculated that her heart needs soul coins to operate. But when you use a soul coin to operate an infernal machine it tortures the soul to death and it screams entire time while its soul is being burnt away - see 4:45
I honestly kinda doubt that. Soul Coins are a rare thing. It is actually possible to miss them all. So, does that mean that those who do not explore (and are to late to save a certain Tiefling) can not actually use Karlach? That makes little sense to me.
Soul coins and the mechanic of that will certainly be interesting as will whether we can do anything else with them without Karlach. But Karlach herself is good aligned...maybe a bit too good aligned as I am not inclined to take her as part of my party. I'm sure she's not keen on having that thing in her. I wonder what happens to the infernal machine if we kill her. I am inclined to think it might be a lootable item that might be put to other uses and thus providing usefulness for soul coins without Karlach...or if a particularly evil character might want that thing put in him to increase his power. A situation not too different from Gale and his Netherese Destruction Orb.