Overview of the Issue
If you create a custom category template using the WordPress Site Editor (formerly known as Full Site Editing), the translated template may not display on your site’s secondary language. Instead, the default theme template is displayed.
Workaround
This issue is fixed. Updating to the latest version solves it on your site, so you only need this workaround if you can’t update yet.
Please follow this erratum for accessing to its workaround and more updated information.