When you said she's playful, I thought of the name Roxy. I think it works nicely with your style of more "old-fashioned" people's names too.
The cinco de mayo reference is kinda cool, but I think Cinca doesn't sound great out of context and requires some explaining to make sense (just my opinion). You could still go with a Spanish name but something more traditional, like Alma which is in keeping with your other pets' names but gives your pup a Spanish twist. The name means "soul", which has a nice spiritual side.