Damyon, I'm not sure which of three things you're wanting. Two are included in the CSS I suggested, the other I've never seen implemented anywhere. I think you're wanting the first case, which is included. This is easy:
<div lang="en-us">Flashlight</div>
<div lang="en">Torch</div>
That's the last bit I mentioned in my initial post "the most specific language first (the en-us version would come before the generic en version, unless they are one and the same)."
You can also do this, where multiple languages have the same text:
<div lang="en es">soda</div>
<div lang="fr">soudeo</div>
Are you saying you'd like to do this?:
Write text in Spanish and in English.
Some users see the Spanish text.
Some users see the English text.
Some users see BOTH the Spanish and the English.
Indeed I don't think that's supported in Moodle, and if it's supported in HTML I'd like to see a reference for it. The specs I've read gives a list of languages by PRIORITY, and it uses the ONE language with the highest priority.