Specifically, I want := to show up as ≔ in my buffer, and export as such.
If I do…
(add-to-list 'org-entities-user
'(":=" "\\coloneq" t "≔" ":=" ":=" "≔"))
I need to add a backslash before the symbol. Is there a way to achieve what I want?
Entity syntax involves backslash. As an alternative, you may define a custom export filter + custom font-lock keyword.