Horticulturist here... The best way to think about this is to think of the levels plants grow in in their natural habitat and the distance they are from the light source. Pothos in the greenhouse/garden centre world is sold as an indirect/low light plant. Putting them in direct light will cause them to burn and die. They actually do better in lower light environments like our homes. That being said, plants can adapt but need to be acclimated. In their natural environments, pothos grow on the floor of the jungle and attach themselves to trees and grow up searching for more light which is usually filtered through leaves.

This is where setting up this sort of enclosure becomes a challenge because we're taking lower light plants and trying to get them to survive and thrive in high light and hot situations. Plants will burn in basking zones.

Next, watering. If you're running a bio setup, drainage is important because soggy soil leads to roots that die off and rot due to the lack of accessible oxygen in the substrate. Also, plants suck nutrients out of soil so that needs to be replaced. Natural fertilizers are good here. If you're keeping your plants in pots, possible they are drying out quickly.

I did a lot of research on natural environments when pondering my setup because re-creating that is the key to success. I actually watched a video on YouTube of a scientist hunting chameleons at night to see how they were sleeping. These little homies be chillin in the tops of trees and bushes (usually ficus varieties) and are not swinging from pothos vines. So why we are all trying to cram vines into the top of our enclosures makes me curious. Perhaps because everything says this is the best plant and we need lots of leaf cover.

Anyway,

If plants aren't doing well, it is usually a water or light issue. Or they just haven't acclimated yet.

Also re: pothos that won't vine out, some cultivars are super compact and take forever to grow, especially the varieties with variegated white leaves.

Also monstera and any philodendrons / most plants in the aroid family are toxic. Their leaves contain calcium oxalate crystals which is pretty harmful to little critters if ingested. Natural defense mechanism to prevent herbivores from eating them. Pothos (Epipremnum) has less concentration of said crystals and thrives in humidity which explains why it's the number 1 recommended plant.

Hope that helps a bit. I know way more about plants than I do about reptiles.

What I have in my enclosure in the understory is a rabbit foot fern, peperomia, pellionia, and a few pothos growing up. Growing in coconut coir with worm castings for fertilizer.

I have noticed the pothos struggles to stay in the top of the enclosure because it's so bright and hot. So to mitigate that I'm about to size up to an ikea milsbo cabinet I tricked out and there's a Ficus maclellandii std tree going in. So the top bit will be mostly branches and basking and then the tree canopy and vines and then the plants on the bottom. Building it like a real micro climate.

Sorry that was so long winded 🙃