> This seems like such a distant yet specific relationship type

I don't know much about it (never stepped foot outside EU/NA) but apparently some Asian countries have a pretty intricate system of kinship terms. For example Diagram IV in [1] shows different (Mandarin?) Chinese terms for what we would just call a "cousin" in English. I also found the video by NativLang [2] on the topic pretty interesting.

[1] https://ac-journal.org/journal/vol3/Iss3/spec1/huang_jia.htm... [2] https://youtu.be/YOi2c2d3_Lk

Informative! Thank you!

My first guess is that there exist human languages in which there's a distinctive word for that relation. (French, for example, has "cousin/cousine" for a male cousin or female cousin, which is about halfway there.) I would guess this is used when translating into those languages.

For example in Hindi, where the words indicate whether someone is on your mother's or father's side, and also something about age:

https://anilmahato.com/55-family-relationship-names-in-hindi...

(His transliterations seem "phonetic", by the way; e.g. I think you normally write "-ji", not "jee", and so on.)

Or, this looks a little more "legit", but actually harder to understand for an ordinary English speaker who doesn't know linguistics:

https://omniglot.com/language/kinship/hindi.htm

Anyway, between the two, you get the point.

(I'm not especially expert here, but figured I'd mention this because nobody else had yet.)

To me, many of these words sound like almost childish terms of endearment -- a little charming.

Anyway, this is not at all academic for someone who wants to participate in the culture, because everyone around you is going to be identified and addressed in this way, and you're going to have to know who everybody is! Even if, in your head, "chacha" is not some abstract relation, but a particular person.

English has some uncommonly used relational terms, like "second cousin once removed" or "great-nephew", which are comparable in complexity. If you're feeling creative, you can even stack on some confusing modifiers like "step-" or "-in-law".

Yes. There's an option to add "related contact". I'm not sure what triggers the full flow, but normally it shows three options, and eventually you can get a larger list of 15 or so expected options (mother, father, brother, spouse, etc). And an option for "all labels" that leads to the mess hinted at by this constant.

I'm not sure what the point is, since you also have an option for a custom label, which even if I wanted to add a link for the "younger cousin (mother's sibling's daughter or father's sister's daughter)", I'd probably type in whatever I call that relationship informally as a custom label before selecting that mess.