One thing I spotted when playing with your awesome quoting UI, was that the Quoting hover preview (see the image if you're unsure) didn't locate the quotes location within the entire body of text.
Here's a non-artistic example of what I mean -
I feel that just simply highlighting the quoted text in this hovered version, allows me, and others to add context to that text very quickly by locating the text before or after the quote, without needing to read the entire message.
I believe that this could also be applied when the user clicks on the hovered preview > is brought to the original > then sees the text highlighted. This highlighting should then disappear when the users click somewhere else.
This is mainly to avoid moments in forums when someone isn't perfect, and they're just not 100% optimal at quoting text. Yes the current system work in eliminating a lot of the issues found with this common forum problem, however, if there are paragraphs of text in the original then there's going to be a nightmare for people to find the quotes source location within the original.
Hope this helps