Yes, the version check is there because it is hard to have a foolproof way to check if the changes are compatible or not.
The update is very simple, so something like this SQL query should be able to revert the update (not tested!):
CREATE TABLE "BackupTemp" AS SELECT "ID", "Name", "Tags", "TargetURL", "DBPath" FROM "Backup";
DROP TABLE "Backup";
ALTER TABLE "BackupTemp" RENAME TO "Backup";
UPDATE "Version" SET "Version" = 5;
It should ideally just DROP COLUMN "Description" FROM "Backup" but SQLite does not support DROP COLUMN