So, I headcanon that most of the Chicas can speak Spanish, including the main Chica. I like to think that Chica would teach Bonnie a bit of Spanish, so he'd probably be a beginner-level Spanish speaker.

However, Bonnie is just so four-impaired that he can't even say "cuatro" right. He says "cuotra".

The same kind of thing would also apply to any other language he spoke, though he only knows English and Spanish at the moment.

It makes absolutely no sense to anybody, though Foxy is the only one who really cares.

(Bonus headcanon: Cupcake can speak Spanish as well, though his equivalent is just saying "¡Soy una Magdalena!")