Thus the inherent contradiction: Unicode is for text, it must include all existing character sets which it aims to unify, and previous character sets weren’t only used for text.

The obvious hack is to make a custom character set called “Rejected by Unicode”.

The goal was to eliminate "we can't switch to Unicode, it doesn't have ® symbols" objections.

It would probably be easier just to design a png or svg icon for the UI widgets you need. Then you don't have to lobby a consortium and wait for them to accept your icon.

To offload the design to the font foundry is even easier :)

Unicode Russell's paradox

Isn’t Wingdings just a font that can work with whatever character set?

Yeah, it was basically a hack to extend the character repertoire in the time of 8-bit character sets. The kind of shenanigans Unicode was designed to replace.

You still see this kind of mischief when Outlook users type a smiley, and it is rendered as a "J" with the wingdings font. Readers of the mail where styling is stripped or who haven't the font installed just sees a confusing "J".