[cja]

How to use Syncthing on Android now that the app has gone?

[TheFreim]

There is a fork: https://github.com/Catfriend1/syncthing-android

[s2l]

For this type of data, preference could be toward fully open source stack (i.e. fdroid, etc).

Another thing I recommend is to enable versioning on syncthing for the database. This way accidental changes can be reverted easily.