Xwiki 2.1 Syntax / CKEditor: Buggy Behaviour with Groups / Embedded Documents and Lists

Groups / Embedded Documents using ((( ... ))) frequently cause hard to understand and very intransparent behaviour - and if you use copy paste can unexpectedly suddenly appear in your document.

I think this is a major usability problem and can imagine it can be a hurdle for Xwiki adoption, or at least acceptance among its users.

We're an IT shop and (nearly) all of my users are software developers themselves (but no experts in Xwiki internals), and even they struggle with Xwiki editing behaviour - the most frustrating behaviour ("It just does not do what I want it to or expect from it!") caused by implicitly / unintentionally added Groups / Embedded Documents.

See the following example - I want to create a list and copy some text to one of the list items.

Now suddenly the spacing between the list items below the pasted item (Items 4 and 5) is much bigger than the spacing of the items added before - and the user does not seem to be able to do something about it in the WYSIWYG editor.

When adding new subitems now, it mostly still looks fine - except for the spacing - but as soon as I save the document, the whole list layout is messed up:

This is the resulting Xwiki markup:

* Item 1
* Item 2
* (((
= Studie zum hybriden Arbeiten: Die Idee ist gut, doch das Büro noch nicht bereit​ =

Eine Studie zum hybriden Arbeiten zeigt: Die Rückkehr ins Büro wird eher von mangelnder Ausstattung als von mangelnder Bereitschaft der Angestellten behindert.​
)))
* (((
Item 4

* 

Item 4.5

* 

Item 4.6
)))
* (((
Item 5
)))
* Item 6

In order to fix the list layout, you have to enter edit mode again and fix every incorrectly formatted item one by one.

Regarding the Groups / Embedded Documents included here and there in the list and the inconsistent spacing it adds, the only option seems to be to edit the document in source code / markup mode.

And even then, getting rid of the Groups is cumbersome, because the sub list items within the Groups have the wrong nesting level once the Group is removed (because the whole Group was nested before), so the nesting level also has to be re-adjusted for every single list item.

And this can become really difficult, if the lists are larger or more complex, or the list item contents are more complex...

Also, these were just a few examples - lot's of other not-immediately-obvious behaviour results from unexpected Groups / Embedded Documents occuring somewhere in the wiki page, frustrating my users.

Is there any easier way to fix / adjust this or manage Groups / Embedded Documents (adding, removing, and making there presence more obvious), which accidentally might get introduced any time without the user even noticing?

This is reproducible.

• Xwiki LTS 15.10.7
• Browser Chromium Version 122.0.6261.94 (Offizieller Build) snap (64-Bit)
• Ubuntu 22.04 (KDE neon actually)