They can take over 85 .... my greenhouse gets up near 90 on a sunny summer day. However, there is a misting system and exhaust system. So the air is fresh and moving. I would say that much over 85 in an enclosed terrarium could be risky even with fans blowing the air around because your lacking the fresh air exchange you find in a big greenhouse or out in the wild.
It's just a matter of getting to know your setup and the plants and how they respond in your situation. If the pitchers lids start drooping then you know something isn't quite right. Otherwise they are probably fine.