SyntaxOutlaw
I'm also excited about this extention! Thank you for working on it!
Since by default all replies are stacked chronologically, rearranging the nested threads can be confusing in certain discussions. Discourse lists the discussions chronologically, but under each post which got direct replies, you see a text "X replies" like "1 reply" or " 3 replies" which when clicked will additionally unfold the replies nested underneath. Also under each reply you have a "Jump to post" link which will exactly do that.
You can check the behaviour for example here: https://www.elektronauts.com/t/buffer-playback-erasing-itself/236061
I'd love to have it work in such way that you can use "show X replies" and "jump to reply" for the corresponding posts. I think it is a thoughtfull and convenient way to deal with the nested replies.
(Unfortunately i cannot test your drafted version yet, as my webhosting does not allow to compile, but I'm looking forward to test a compiled version when published)