Russian name, English slug-> subsidized by #category_eng_slug, engl tag looks not natural in rus text.
Russian name, Russia slug -> Not subsidized at all (drop down with Russian categories shown), just plain text #category_russ_slug, no links after ENTER key.
Also, non technical issue - good to have english slugs (and russian name) for some SEO and other purposes
While this would probably be the most common use case, this feature would also be relevant for English fora where the slug does not match the category name (for whatever reason). For example, I have a “Say Hi” Category whose slug is instroduce and whenever I ask new users to write a quick introduction in that category I have the choice of writing “say hi category” (and possibly linking it manually) or to write “#introduce category” which autolinks nicely but which is potentially confusing to users because there is no category called “introduce”.