Yes, there was a notice at the top of my dashboard saying something like 'Multisite Language Switcher Setup is incomplete. Click here to configure', but that has gone away now.
I have just noticed that when I go to create a post, after I hit 'publish' this error message comes up:
Fatal error: Call to a member function get_language() on a non-object in /home/freeespa/public_html/[redacted].com/wp-content/plugins/multisite-language-switcher/includes/MslsMetaBox.php on line 144
The post still posts, but initially all you see is this error screen.