Thanks, Chris, this is exactly the discussion I'm looking for (though I wasn't quite looking for it then!).
We're moving from a bespoke DITA-to-Confluence system to a static site generator (Hugo). We have to refactor our links (and our file structure) and I'm hoping to take this opportunity to Keyref All The Things, just wasn't sure if this was the 'right' way to go.
I may be reaching out offline :)
I should also add a huge thanks to Radu who sent over an XSL solution.