@sleepyfoxscanlations Hm... fair, kinda, I suppose.
See, problem I see (and I say this coming from a translator who also happens to be probably a bit more literal than we should) is that it's a slippery slope. We all know the meme, "everything went according to keikaku", yes?
I mean, as I said, onii-chan makes sense, kinda sorta. And your point on the different ways of addressing your parent is valid. But we also have that in English, or Spanish, or many languages? Mother, Mama, Mom, Mum, Mommy... (Not exactly equivalent translations, but if you catch my drift). "Hahaue" is, I'd say, so uncommon that it may warrant no-translation. But Kaa-sama is a direct Mother. Kaa-san is, I'd say, a direct Mom (mom feels a bit softer, but I'd say they're equivalent in that they're the "standard"). And for Kaa-chan you could go Mum?
You also have a point about "knowing the culture" (that IS one thing that a fansub has an advantadge with when compared to official translations, we can be more flexible with that). But still, where does it end? You actually added a note about almost leaving the "nieces". Really? Okay, then would you leave "brother in law" in Japanese too? Let's also leave "osananajimi" instead of "childhood friend", since that's a VERY common Japanese thing, but I don't think I've ever read it in English outside of manga.
I mean, how many ways to addres the niece/nephew are there? And is it relevant to the story/translation?
Hm... Sorry if I sounded aggressive or pushy, I don't mean to. But I think I mentioned in a past chapter that I happen to be a translator by profession, and have been part of several fansubs myself, so when I see these things I wonder about the thought process of the person doing the work. Figured I'd ask, nothing else.