Levistus's_Leviathan
5e Freelancer
Agreed.1) Karlach now (and at the time the quoted post was written) has more of an ending than literally any other character, and in fact, her ending kind of overrides a number of other endings, potentially. Yes this was patched in after fan response, but it's no more "unfinished" now than a number of other characters. Arguably now she can have one of the most positive endings vibe-wise, albeit one likely to feature strife and struggle.
2) Karlach has white-approximating facial features in her current version, and is played by a voice actor doing an accent - sort of in-between Received Pronunciation and Estuary - that is very much associated with white Londoners. The idea that she's "non-white" in some way that would cause her to be victimized by the writers because the voice actor isn't white - something that's quite hard to find out, note (it's not obvious from her appearance) - is not particularly convincing.
And Karlach had a better ending planned, but it was cut due to the developers not having enough time to implement it. Like how they cut an entire companion from the game due to not having enough time to implement her (Helia the Halfling Werewolf Bard). And it's possible that Larian could add some of the cut content in a Definitive Edition, like they did for Divinity: Original Sin 2. Not to mention the fact that Karlach has less quest content than most other companions because she was one of the last companions to be added to the game during development.