I don’t know much about them either, but first cut off affected leaves — dead areas will just attract mold/fungal disease. If you had used some kind of spray with oil in it, that could have caused sunburn as well. Another semi-common patio plant casualty can be result of unthinking guest pouring unconsumed alcohol in the pot. (Be sure to educate your guests on proper etiquette around potted plants
If it seems like too much sun, consider moving them — it’s also possible it is getting reflected heat ...is that a wall? So moving away from the wall to allow for some air circulation might help.
I think best to be out there with the plant during different times of the day to check on sun exposure and just how hot the sun/air feels to your own bare skin.
You could also set up some shade cloth or awning over the plants if they can’t be moved.