@BurningTreeC thanks this is awesome. I can see you are putting in substantial effort.
I would suggest each feature that makes using the editor to write and build TiddlyWiki, and for that matter writing other code, is introducing substantial productivity tools. You may not get to see it personally but the help it is giving and time savings that is going to be available indefinitely to the community and of extreme value. Better highlighting of wikitext and TiddlyWiki script is a key love of mine.
Just a little question, or something to think about,
Things like link preview and navigating to tiddlers from edit mode are wild. I am wondering if there could be a way to bring the link preview into the viewTemplate with a simple tweak that makes use of your existing code? There may be other cases where the internal code makes sense to bring forward into the view template, optionally and perhaps in a dedicated plugin “Reuse codemirror6 code in the viewTemplates”.
An issue
However I see this happening in links within “WikiText Syntax Sample Tiddler” on the demosite.

Then I create the missing tiddler I get;

I remain curious as to the underlying message.
[Edited]
I also wanted to say having the linting (new word for me) is fantastic, I see in this example the ability to correct the error

- Once selected the options disappear. I am wondering if one could have access to this when refactoring code without errors?. An example would be selecting the application of a closing widget to a self closing and never mind the new error message that occurs, its will be easy to correct.
Thanks again