I just wanted to touch upon the fact that although both Hispanic, Jaime and Eduardo don’t speak the same kind of Spanish. Which is huge to me, being half Mexican and half El Salvadorean, I know that there are huge differences in dialect between Spanish speaking countries.
Eduardo is from Argentina and his accent shows that; South Americans in general, have softer consonants than Central Americans or Mexicans. He also uses Spanish words more liberally than Jaime, which probably means he spent more time speaking Spanish, seeing as how he used to live with his grandparents. Older generations usually either insist on children speaking Spanish at home, or cannot speak English themselves making it necessary.
Jaime’s accent is not a thick as Eduardo’s meaning he was either born in America or raised in America from a young age. He probably can speak more English with his parents, which is why he mixes them both together in a very Spanlish manner. Also ese isn’t used in Mexico and is almost an exclusively Mexican-American thing.
In fact Young Justice has always been very good about accurate Spanish accents. In the episode Drop Zone, you here a Cobra minion speaking Spanish in a heavy American accent, which is fine because he’s obviously not supposed to comfortable with it. Bane on the other hand has a distinctly Caribbean accent, indicating that he is either from Puerto Rico, Dominican Republic or Cuba, where I suspect Santa Prisca is probably located.
The fact that I can tell that from the accents is telling of the creators respect and understanding that Spanish is nowhere near a one-accent-fits-all kind of language; which is very refreshing not only in animation, but in media in general.