Translation of metaphorical meaning of "hieroglyphic"

Question

To literally translate "hieroglyphic", when referring to a largely logographic writing system used by Ancient Egyptians, I think ヒエログリフ or something similar would be used.

However, there's another, metaphorical, meaning in English to the term "hieroglyphic", which is writing that's hard to understand, possibly because it's too advanced for the person reading it as opposed to it being sloppily written. (Meaning 3 in English wiktionary)

Are there any terms in Japanese that use metaphor to convey this metaphorical meaning?

Answer 1

Another (more) common English idiom for this is It's all Greek to me and Eijiro offers an interesting word which I haven't encountered before:

Don't ask me anything about computers. It's all Greek to me.
私にコンピューターのことは聞かないで。ちんぷんかんぷんなんだから。

The theory seems to be that the word appeared in the Edo era and made fun of Confucianists who liked to use a lot of obscure words of Chinese origin, or possibly mimicked the unintelligible speech of foreigners.

However, this word seems to be mostly about speech, or the ideas being explained, and not the writing itself.

Answer 2

[解読不能]{かいどくふのう} would be the only word I could think of. It literally means "indecipherable" but it could also be used when the writing itself is in one's own language (and letters/characters) but is too difficult to read.