The tool works very well when translating a whole article. In my experience, it also happens that an article exists in languages A & B and that only a few sections need translating. There are only two options available now : 1) not using the tool 2) creating an article with a new name B+, translating the necessary sections in B+, merging B & B+, deleting B+. It would be great to be able to use the tool to translate a section directly into an existing article
Topic on Talk:Content translation/V2
Thanks for the positive comments about the tool, @AnTeaX.
As you mentioned, the main focus of the tool is to start an initial version of a new article. Currently, as you described, there are some workarounds that can be made to expand existing articles but the workflow is not very fluent. We plan to improve this process in the future (check this ticket for more details).
Having said that, our main focus right now is to complete the work on version 2 for the translation editor. we want to replace the previous version of the editor before adding additional capabilities such as expanding existing articles. In this way we can bring the updated version to all translators and no longer need to maintain two different versions of the editor.