> ␛ is just keyboard syntactic sugar for control left square bracket

Technically — and here I go of on the stereotypical irrelevant nerd tangent (bind the adjectives as you will) — it's the other way around. ASCII was certainly designed with Shift and Control modifiers in mind, and arranged so that a device could have those keys merely flip a bit (see e.g. <https://en.wikipedia.org/wiki/Bit-paired_keyboard>), but nothing actually mandates that those keys exist and that Control+h generate Backspace or Shift+h generate H.

I absolutely agree that Control+x ↦ x&0x3F is an established convention, and it continually annoys me that Windows and Windows-aping software violates it.