Two simple tips I suggest for groups having difficulty with elements:
1) Make sure to turn down all party effects. I know it's not directly related, but the less visual confusion... the better.
2) Go into your system configs and make sure your status debuffs are prominently displayed on your screen (not tucked somewhere where you have to look at something like a party list in the upper corner to notice). I moved mine right above my hot bar and upped to 140% just for this fight. Handling thunderstruck will never be easier.

Good luck and hope you guys get your clear.