Isn't Kai'Sa a human with a symbiotic relationship with a void creature? She has a name similar to the other voidborns (Cho'Gath, Kog'Maw,Kha'Zix,etc.)
I believe she once had a human name but when she got stuck in the void, she forgot her real name and adopted a voidborn name or something like that.
I don't actually think it's a Voidborn name. There's some overlap between those and actual Shuriman names.
It could be similar to (if you watch Stargate) with the Goa'uld.... its a symbiotic relationship but the Goa'uld goes by its name, which could be the entire life of the humans body. The symbiotic suit could be Kai'sa, and the human is not able to control anything. Could be interesting to find out the real thing if this is not the case.
She could've forgotten her name, and the civilization she met after she exited the void called her "Kai'Sa", after the ancient Shuriman naming conventions that are used with most Voidborn. That's just my theory, though, yours is also definitely a possibility.
All void names are made up by shurimans so her being from shurima before she got in to the void ...doesn;t change her original name
