ahmedfromtunis's comment was killed, presumably because he attributed it to Gemini, but it was correct on the facts. Here's the response I wrote to him:

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Count of symbol types is what you'd look at. You have a bunch of unknown symbols, so there's nothing else you can look at.

For comparison:

Japanese hiragana: ~71 symbols [*]

Cherokee syllabary: ~86 symbols

Greek alphabet: ~24 symbols

Latin alphabet: ~21 symbols ( https://ancientgraffiti.org/Graffiti/graffito/AGP-EDR187776 )

[*] Many Japanese syllables are spelled with digraphs ("sh", if the "h" appeared in a special combining form) or diacritics ("è", if è and e were completely distinct sounds, as they are in French), which lowers the memory burden. I've counted diacritics as creating new symbols and digraphs as not doing so.