That is a shortcoming in the english language.
In german we (and the Jolla devices) say "Auf Wiedersehen" which is nicely formal and perfectly translates to "See you later".

But i guess the Alligator rhyme made it informal forever in english?
If not, propose the translation officially sir.

@stickymick, you are not alone. I also had that on Xperia X and nearly gave up.