Could someone who understands what the proposal is trying to say edit it to actually do so in clear English? What exactly is it asking for that's not already done by MediaWiki's existing diff functionality? Non-accessible colors (red/green versus blue/yellow)? A unified-diff option? Somehow mixing diff-highlighting into the syntax highlighting in the edit box?
Topic on Talk:Developer Wishlist/2017/Backend
I tried to clarify in the task without much success. My best guess is that it asks for unified diffs and prettier presentation.