I work with Simple English. Language comprehension also has a lot to do with some (probably boring) statistics: Shorter sentences are easier to understand. That way, a tool that would give the avg. sentence length (eg. for the section just translated), or that would point out sentences that are longer than average (or lonher than a predefined length in words) migfht be useful.
Topic on Talk:Content translation
Hello Eptalon,
Thank you for your suggestion of having a sentence length indicator feature in Content translation tool. You can also make this suggestion in the ongoing Community Wishlist Survey for better visibility and community voting.
This request might be similarly useful for the editor in general. Doesn't make too much sense to me if this is only implemented within the content translation interface.