To restore a backup you can follow the original instructions here: https://dsmr-reader.readthedocs.io/nl/v4/faq.html#how-do-i-restore-a-backup.
If you are using the TimescaleDB addon, you could to use your own machine to restore. You can Google how to do this: https://www.google.com/search?q=Restore+a+database+with+psql&oq=Restore+a+database+with+psql&aqs=chrome..69i57j0i19i22i30l3.663j0j4&sourceid=chrome&ie=UTF-8
To connect to the TimescaleDB from you machine you need to expose the portnumber in the TimescaleDb add-on. Correct me if i’m wrong, @Expaso?
Edit: Nice, seems it can be done directly on Home Assistant as well DSMR Reader Add-on for Home Assistant