Frankly I'm willing to bet hard money that any pagan sacred sexuality fire festival is a LOT more likely to get the old juices flowing than a place like that or Hedonism but who am I to say. I assume the place you guys went to was clothing optional and you could see or hear folks getting uh, friendly (by accident). You can practically trip over people having sex at some of these festivals.
You got your answer though, seriously. If you were in that environment and she froze then tell her to stop worrying about it. If she ever really wants to do it, she will, stone cold sober, drunk or whatever. Anything she takes to reduce her inhibitions that's stronger than alcohol or weed is just going to make her black out which basically defeats the entire purpose.
Look, 95% of the time fantasies do NOT live up to their expectations. Maybe at her heart she doesn't really want to involve another body in your bedroom.
Try Tantric sex, seriously. Way more interesting and enlightening, and it will do things to your relationship and sex life that you wouldn't have dreamed possible. Makes that mundane one night thrill stuff look like preschool.