LangDesk: Translation Roles for Polylang

LangDesk turns a multilingual Polylang site into a tidy workspace for translation
teams. Assign one or more languages to a user and they can only edit content in
those languages, while still being able to read the source language to translate
from it.

• Per-language editing. A translator can edit only the languages assigned to
  them. Other languages stay readable but cannot be changed (fail-closed: enforced
  at the capability level, so it also covers the block editor / REST API, quick
  edit, bulk edit and page builders).
• A clean working view. A restricted translator’s post lists default to their
  own language, so their content is always front and centre, instead of the
  all-languages mix. A “To translate into X” view filters to the source-language
  posts, where Polylang’s own “+” creates the translation.
• Composes with your roles. LangDesk only restricts by language. Whether a
  user can publish or only submit for review still follows their WordPress role.
  Site managers (manage_options) are never restricted.

Requires the free Polylang plugin.