The package seems unmantained but there's a bug report at
https://github.com/emacsorphanage/key-chord/issues/10

I can't tell where the bug occurs and for what reason so the reports are
duplicated until better judgement.

On Fri, Nov 10, 2023 at 7:58 PM Eli Zaretskii <eliz@gnu.org> wrote:

> > From: Everard Nisse <everard.nisse@gmail.com>
> > Date: Fri, 10 Nov 2023 16:15:04 +0100
> >
> > With Flyspell mode enabled, key-chord combinations are ignored until
> Flyspell has finished marking
> > incorrect words, chord characters are typed instead.
> >
> > To reproduce
> >
> > 1 Install the key-chord package from MELPA
> > 2 M-: (key-chord-define-global "jk" "testing")
> > 3 key-chord-mode & flyspell-mode
> > 4 Type and quickly try to invoke the "jk" chord (press both keys at the
> same time)
> > 5 Result should be "testing" being inserted in the buffer but instead
> the chord is ignored and "jk" is
> >  typed
>
> Thanks, but why do you think this is a bug in Emacs and not in
> key-chord-mode?  Did you report this to the developers of
> key-chord-mode?
>