https://news.ycombinator.com/item?id=36809624 ("Typesetting Rare Chinese Characters in LATEX")
Arranging fleurons is great, but that seems it should belong to the realm of word processing layout or drawing program arrangement, not something at the Unicode/font level.
Complex fleurons aren't graphemes; they're illustration.
So do [combining characters], yet they're valid Unicode.
And obviously those combinations don't exist in any actual writing system. It's a (funny) abuse of the Unicode design, not the intention of the design.
Also, the original suggestion was for Unicode to add ornamental combining characters. I don't see how that would require any breaking change. You can already stack them vertically and horizontally.
https://en.wikipedia.org/wiki/Tibetan_script?useskin=vector#...
Edit: I've scrubbed it out of your comment and put the formerly zalgoed text in [square brackets].
> Complex fleurons aren't graphemes; they're illustration.
The line between writing systems and illustrations is pretty blurred, if you look closely enough. Especially now, with composable and even AI-generated emoji. (I wonder if they regret including emoji now...)
I wonder how far one could take it with just ligatures?
Very, very far...