Zanata was only able to run the translation copy mechanism on newly pushed documents and used a very conservative algorithm to find matches (same document name, same translation context and content).
Project Maintainers were only able to invoke the translation copy functionality at the same time they were pushing documents. Also, this meant that maintainers were not able to reuse some potentially reusable translations (such as those that belong to documents that moved to a different directory).
Implemented an option for Project Maintainers to invoke a translation copy from the GUI (project version page).
Project maintainers are now able to invoke a translation copy at any time, with some customization options. Since the process is now applicable to already existing documents, Zanata makes sure that only a single Copy Trans is running at any given time for a project version, and will prevent any user from starting another copy trans if another is in progress. It will also show progress information for any ongoing translation copies for a project version.
Also, project maintainers are now able to slightly customize the sensitivity of copy trans. The user can select which actions to take when a translation matches, but its document name or its context doesn't, entirely disregarding the translation, reusing it but marking it fuzzy, or ignoring the mismatch and reusing it.