I'm setting up a Drupal 7 site that has 11 languages installed.
Original content is in English and we have dedicated translators in different countries who will translate the nodes to their language. But we do not trust the translators, so we would want to limit their access to just do the translation in their language for each existing node we have.
They shouldn't be able to create new nodes (except when creating a translation) or edit nodes in other languages.
We have set up roles for each country so we can assign any number of translating people to those groups.
I've now spent the whole day trying to figure out how to achieve this, with no luck.
I even wrote a module to address this issue, but unfortunately it seems it is an impossible task.
The module adds a permission setting per installed language in the permission management page, and I use it to limit the create and edit access based on the nodes language.
This doesn't work for the translation links in the translation tab as there's no way for the node_access() to know what language node the link will create or edit. This is not a big problem, as long as I could get the node edit and creation pages to be restricted, which I can't seem to do.