restoring the whatsapp chat history from its own backup worked every time i tried it.

Maybe the backup was created by an older version of whatsapp than the version you were trying to restore to?

A backup solution like “seedvault” which is built in to lineageOS might help. It includes settings like wifi passwords, app-data and the apk’s.

Since seedvault is integrated as a system app in lineageOS, it doesn’t require a rooted system like titanium.

There are some limitations though, for example some apps don’t allow backups and seedvault respects that setting.

A “database of fingerprints” would only contain checksums

that’s the case for fingerprint readers in phones/laptops

But does that also apply to prints collected for government ID cards?

you would need to have created a snapshot beforehand.

Then you could restore to the last snapshot. But you would need a live system to do that, if your installation is broken