The word your family actually uses.
Not a translation. The thing itself.
In Hindi, your father's elder brother is your Taya — ताया. Your father's younger brother is your Chacha — चाचा. They are not the same person. The language knows this. English does not.
In Yoruba, Ọmọ Ọmọ is the word for grandchild — literally "child's child." In te reo Māori, a grandchild is Mokopuna — precious descendant. In Akan, both grandfather and grandmother are Nana — a title of honour that does not need gender to carry weight.
Every network sets its own language. ECO renders all kinship labels — the Energy Tree, the family directory, the globe — in the words the family actually uses.
When you create a network, you choose the kinship language. Every label in the network — the Energy Tree, the family directory, the hover cards on the globe — renders in that language. The network speaks the way your family speaks.
Every member can suggest personal overrides — the specific word their branch of the family uses, the regional variation, the nickname that is more real than the formal term. Overrides apply to that member's view. Approved suggestions go into the shared library.
New languages are added when a new community joins ECO and brings their vocabulary. Coast Miwok kinship terms are in the library because a Coast Miwok network is in ECO. The library belongs to the communities that fill it.