> Maybe, it will be interesting if the engine could make a backup
> automatically after a certain number of transactions.

There are already many tools that are available for backup and
restoring Firebird databases.

www.firebirdsql.org
Download -> Third Party Tools and Libraries
Backup / Restore Utilities

I don't think you can equate the number of transactions with the
importance of the information stored. Furthermore, there would be
issues such as where Firebird should create this backup file. Users
who would bother to actually set this configuration would be the same
ones who already configure a scheduled task to run gbak. IOW, I think
it is a solution in search of a problem.

Adam