What you've done sounds right to me. You do need to make sure that any new configuration directives in 2.2.4 make it into your old config.inc.php; this is outlined in docs/UPGRADE:
Be sure to review the Configuration Changes section of the release notes in docs/release-notes/README-(version) for all versions between your original version and the new version. You may need to manually add new items to your config.inc.php file.
... but it looks like you have accounted for this. You don't need to do anything to/with config.TEMPLATE.inc.php.
And yes, if you don't need the other languages, you can go ahead and delete them.