At least bueno was already a word? [cracking up].................ok, that's a good one.
I guess I don't get my own joke, since I was being serious.
My point was that the word hello was only marginal slang at best when the telephone was invented, but Edison chose it to use with the new invention, thereby bringing the word into mainstream English. Bueno, on the other hand, was a perfectly ordinary word in Spanish long before the telephone came to be.
In the early days of the telephone, the catchy new word became so popular that operators were called hello girls. You can research all this yourself if you think I'm making it up.