Apart from the fact that you're wrong geedub....
Your saves are corrupting because you're making them on a firmware which is technically too early to support the game (although many play fine irrespective of this). What you need to do is use Hellcat's Savegame-Deemer on your original firmware that the saves were made on to generate an unencrypted save file, edit the sfo generated, update and then use the plugin to load your modified save on your new firmware.
Instructions are all laid out in Deemer's readme.