How is it an accessibility issue? HTML allows things like little gif files. I've done this myself when I wrote text that contained Egyptian hieroglyphs. It works just fine!

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_flux 3 hours ago | parent [-]

I mean if you don't have sight.

	▲	WalterBright 3 hours ago \| parent [-]
		Then use words. Or tooltips (HTML supports that). I use tooltips on my web pages to support accessibility for screen readers. Unicode should not be attempting to badly reinvent HTML.