If a backup stops with an error before it finishes, the backup file it leaves behind may be incomplete. Part of your data may be missing from it.
Don't treat that file as a full copy of your site, and don't delete anything from your site because you have it.
Run the backup again. If it stops with an error a second time, contact support and tell us the error you saw.
In FW Real Estate, open Data Management and use the Backup tab. It exports your property data as a backup file. The Restore tab imports a backup file made there.
To keep a copy of everything FW Real Estate holds on your site, back up the database together with these two folders:
images/fwre/: property photos, agent portraits and their thumbnailsmedia/com_fwrealestate/addons/: your installed add-ons and designsThose three together hold everything that reinstalling the package can't bring back.