What the API now addresses
The Translations Admin GraphQL API works on resource types, and category URL paths were not one of them. CATEGORY_URL_PATHS closes that, addressing each category as bc/store/categoryUrlPath/{category_id} and exposing queries and mutations to list, update and delete url_path translations.
BigCommerce restructured the documentation around it too, adding a Category URLs page and linking the translations overview to both Category URLs and Product URLs. Product URL translation already existed, which is why a storefront localized before today can be running Spanish or German category copy on an English path.
What to do about it
Treat the first translation pass as a URL migration
A category path change is a URL change, and the old path stops resolving unless you say otherwise. Before running the mutations, list the localized category URLs you intend to change, plan a redirect for each old path, and check what points at them: navigation, breadcrumbs, in-copy internal links, the sitemap, and the hreflang annotations tying each locale version to the others. Doing this on a storefront that has been live in a second language for two years costs more than doing it on one launching next month.