If the liqueur cherries have a stem and seeds will they be allowed into Australia through Australian customs?
Probably yes, but you must declare it.
Commercially processed and packaged foods that have low risk of carrying pests or pathogens can generally be brought into Australia.
However, if in doubt, you should declare it. The worst thing that can happen is that it will be confiscated. If you do not declare and get caught, you may be subject to heavy penalties, including an appearance on a TV show.