Not a mathematician, but:
Mathematics as practiced in the West is a European invention, and it calls for its symbols on European patrimony. That means:
- Roman (italics, to differentiate from text)
- Including Fraktur if you want to spice things up
- And avoiding diacritics, not because they aren’t old (disagree with Martin Ekman’s answer to What alphabets are not used in mathematics and why?), but because diacritics are also used within mathematics, so they’d be misinterpreted.
- I wonder if thorn gets used…
- Greek (avoiding Greek letters that look identical to Roman letters, such as omicron, and half the capitals)
- Hebrew, because it’s the next closest prestigious alphabet to the European patrimony. Even that gets used very rarely: aleph and beth are infinity numbers, gimel is a function; is there anything else?
I’m not aware of any systematic or even ad hoc use of other scripts; Cyrillic would be the next candidate along.
Answers from actual mathematicians welcome. 🙂