Sounds like you don't have celery running. In production celery is intended to be run as a background service but for debugging you can run it in the foreground from the command line like this
change to the piefed directory, then:
source venv/bin/activate
export FLASK_APP=pyfedi.py
celery -A celery_worker.celery worker --loglevel=INFO
Then whenever federation occurs you'll see things happen in the console.
For further help please try the Matrix channel at #piefed-general:matrix.org