Earlier quoted context omitted.
If it's not rendered, then it's not supported. This is very obvious in this case, where the square-brackets have no additional value, but make it just harder to read the text. The links are getting rendered independent of the brackets, so markdown-syntax has no function here.
I think most markdown symbols add semantic comprehension or emphasis value in _plain_ text. That is functional[^1] even here. Including the squared circle for inline links. [^1]: As in functional requirements, is serving to convey the markup intent in a non rich text rendering.
The underscore makes your text worse to read, IMO. Same with the MD anchor syntax.
HN supports italicizing by wrapping an expression with asterisks *. Why insist on a foreign standard?
HN commenters use the [{i}] notation all the time for footnote referencing. Which can be used for links, declutttering the main text.
Why add a ^?