The org-checkbox face does not get applied when using alphabetical
bullets in plain lists. See the attached ECM.

This might be intentional, and if so I'd like to know the reasoning
behind it, but I couldn't find any information about it in the code or
the manual. When checking Org's git history I found that the current
version of the responsible regexp dates back to 2010 whereas
alphabetical bullets were added in 2011, so I figure there's a chance
that it's just an oversight.

Here is a link to the regexp in question:
https://git.savannah.gnu.org/cgit/emacs/org-mode.git/tree/lisp/org.el?h=main#n5852

This issue was reported a couple of years ago but ignored:
https://lists.gnu.org/archive/html/emacs-orgmode/2021-02/msg00395.html

I'm using the latest development version of Org at the time of sending
this email.

Thanks