Normal edit

Let's see...

• The classic editor shows the wiki rendering on "Show Preview" and after you save the message, which has been useful for me to spot typos and errors in formatting, especially in longer messages.
• Ability to change the size of the text box in the Preferences (handy if you're translating a bunch of long messages).
• Also practical for long messages: in the classic editor you can easily scroll the whole page up and down without scrolling the message list along with it and losing track of where you are in it, then having to hunt down the next message in the list. This makes a greater difference if you show a lot of "assistant" other-language translations like I do.
• Access to each translated message's Discussion page (not that anyone uses it, as there is no discussion page specific to a message but common to all its translations).

Perhaps you can make the message name a link to editing the message in the classic editor. It wouldn't consume any additional screen real estate.

For now I've just turned the advanced editor off, the classic one often suits me better anyway.

Added a button for history for now.

What comes to discussion and talk pages, there is Support and results can be added to Message documentation.

Thanks, I guess that will do for now.