Ah, should have known there would be a word for it. Collation. Interesting, and it does look like it addresses the issue. I knew from the start different languages would sort special characters differently based on pronunciation, so this makes sense that you can define different sort schemes, as it were. I was just being lazy and hoping for a magical shortcut that takes the nearest* equivalent from the Latin alphabet and sorts ê like e and à like A, for instance. The previous commenter's suggested function does exactly that, so at least my project now works.
*Poorly-defined, I know. Hence collation being a thing.