Actually, with schema.org possible to describe multiple or the same things: Language - Schema.org Type
Add a property CreativeWork with the URL of http://example.org/c/espanol, with a custom title, description, inLanguage inLanguage - Schema.org Property.
Add them:
https://example.org/admin/customize/themes/1/common/head_tag/edit
Search engines will understand it, that different categories are in different languages to which you can give any title, description etc using schema.org. Each CreativeWork is a category representing a language.
You can add many CreativeWorks into the header as you like.
This way don’t need to mess with modifying discourse at all, while allowing you to signal it to search engines that your main site is called XYZ in different languages.