Oof. The reading for names will always get me. Still worth knowing the name reading!
Google maps has it showing up in a bunch of business names, too.
Seems to have been a bit of confusion in several directions here, but just to clarify: in modern usage 金子 is read only as Kaneko, and is a very common surname. The "kinsu" reading is archaic; a typical native speaker may never have heard of it.