Sxinstaller as well as sxos built in installer is flawed. Use tinfoil,awoo or dbi. Or a variant. The SX installers patch the game and make them unable to load in atmosphere. It's best to make everything correct so you can freely bounce back and forth between SX and Atmo if necessary.
You can only downgrade as far as the game was developed for. The game has requirements. Then it is encrypted to the newest keys for copy protection purposes. That's why some work and not others.