I just wanted to direct you toward a better and more recent implementation.
But, sure, if you use the other one, and it's buggy, it should be fixed, as
long it's still around, in the official code base.
You're quite right, and indeed I did try capture some time ago, couldn't immediately make it do what I wanted, and left a FIXME in my Emacs setup to return to the problem at some later date.