This occured to me while watching "Red dwarf". In the show, signs in the mining ship are bilingual. English and Esperanto.
Kerbals are known to speak gibberish which is, contrary to the myth, not backwards Spanish, although the source speeches we hear in early Squad do contain some Romance language words, sometimes jumbled up.
Since Esperanto sounds a bit weird and needs getting used to, but is very easy to learn, and as a homage to cult comedy SF series "Red dwarf" why not make Kerbals speak Esperanto? Maybe even backwards Esperanto to make it more enigmatic if it suits the ear.
I think it's a great opportunity for the game to use something international.