Cyrillic categories

There is a problem.
When i name my categories on russian or other cyrillic language and then start using “clean url” and i’ve got smth like this
https://blog.com/categories//
the same with post names but there is a “POST SLUG”…
is there a “category slug”?
or what should i do with this problem?
is there some progress in this direction in nightlies?
i’ve tried to edit “classes.php” but that leaded to complete mess because of .htaccess rules.
some 5 monthes ago there were the same problem with hindy. But may be smth have changed…
TNX in advance…