Did Calanthe keep a ton of girls of other ethnicities in her court? Can't recall reading that in the novels or the saga. So, really? Why would Geralt assume that the one girl looking a little different, where that different look would be
sharing a skin tone (and other ethnic traits, probably) with her foreign father might be indeed his child? Why indeed, just boggles the mind
And it's not like he resigned because he thought their child wasn't there at all, that Calanthe wouldn't risk it at all and as such fighting her over it would be pointless. Changing it to Geralt having reasonable suspicion that Pavetta's child was there and still getting the fuck out without even confronting her about it, let alone without the child in, would totally not be a different outcome (that would heavily influence Sword of Destiny and Something More). Because, like you claimed, it had no repercussions on the story at all /s
And even if Calanthe arranged it so that all of the girls shared the same mixed ethnicity as Ciri, it would still be a change from Geralt assuming that none of them is Calanthe's grand-child to "welp, any of them could be, too much effort, I gotta run" which still shits on his character in that scene.
Also, really? Geralt wasn't expecting a child? What, he can't count how old Pavetta's and Duny's child was going to be when he visited?
And that fictional world was still heavily inspired by Polish folklore, other European myths and culture. So go figure.
A
specific difference in skin-tone matching that of her father with supposedly different skin-tone on the other hand would stick out.
How about you shove that bullshit projection where the sun doesn't shine? You shouldn't have pulled it out of there in the first place. Did I say it's about them being white for the sake of being white? No. It's about being true to the source material.
That is the most important thing.
Especially since the casting, if true, is about non-specific minority. It'd be one thing if they just had a specific vision for Ciri and had to sacrifice being true to that material to achieve it. "Black or Asian or any other minority" is not a specific vision. It's a sign of nonsensical pandering. Changing things just to pander to some group deserves no hope, let alone praise.
Back to your BS projection, did I say I don't care about the Polish series? No. The Polish series was an unholy abomination. Precisely because of how it treated the source material (among other things, Żebrowski's acting didn't help much either).
So hit and miss on your part.