Never had any issues for the animal with having live plants in the terrarium, as long as it is all ventilated properly (Humidity will be through the roof).. And obviously the plants should be harmless, non toxic no thorns etc. The more difficult factor is keeping the plants alive, they wíll be used as pillows.. Their roots will be dug up, or if your snake is anything like my T+ boa it will be flipped upside down. And that is only if they can survive the heat, and if you have enough lighting for the plant to survive.
They love to hide behind them, and it looks great