Generated PDF does not show characters from the "math operators" unicode block
I have created a page with some mathematical formulas.
As Confluence does not support TeX input, I copy-pasted unicode characters from the Wikipedia page on mathematical operators:
https://en.wikipedia.org/wiki/Mathematical_operators_and_symbols_in_Unicode
into the confluence page. This is detail work (i.e. painful and the result is less than convincing, espcially as there is neither a viable superscript nor subscript), but is an acceptable workaround for now (except for the reverse double turnstyle "=|" which does not seem to have a glyph in the typeface I'm using, the characters are well displayed).
However, when "exporting to PDF" all those characters are gone. Indeed, the PDF seems only to support ISO-8859-1 characters? That's like so 1990s.
This documents
yields this PDF
Note that copy-pasting into LibreOffice, then generating the PDF gives an acceptable result:
What can be done?