Julio, I discovered something that might help you. It's call RefTagger, by Logos. The link for their site is here:
www.logos.com/reftagger
It automatically finds Bible references in your web content and displays the Bible text in your choice of a long list of Bible translations. The list of translations is only stated by abbreviation, so I can't say for sure that there is a Spanish one, but it seems likely, because on the main
bible.logos.com website there are a couple translations that look like they might be Spanish: "La Biblia de las Américas" and "Nueva Biblia de los Hispanos". I can't tell if either of those are among the translations that you can use with RefTagger, but it's worth taking a look.
RefTagger might be something for the JoomlaOregon folks to know about. You said:
We are hoping in the future that more Bible translations will provide a web service for us to retrieve the verses. But now only the ESV does that.
RefTagger works differently than your scripture reference code (a little script is inserted in the template index.php, which calls a Javascript file on the logos.com server), but at least it offers more translation choices. You could spread the word to your user community, perhaps.