Which two languages were the possible choices for Mozart's first opera in Vienna?

When Mozart went to Vienna, he wrote two musical pieces which are considered his first operas—the first one was a German singspiel titled Bastien und Bastienne (Bastien and Bastienne), and the second one was an Italian opera buffa titled La finta semplice (The Feigned Simpleton)—both of which were of comedic character.
As the first piece was only shown to a private audience, the second one is actually considered his first, official opera. It was, obviously, originally written in Italian; however, in 1769, the opera was also performed in the archbishop's palace in Salzburg. Thus, the other possible choice of language was German.
It is notable to mention that Mozart was only 13 years old when he wrote these two operatic pieces, which only further proves his genius.