The key to getting plants to flower is high light.
+1. I use a couple of
70W Sansi grow lights (double-wide enclosure) and everything under them grows & flowers like crazy. For a 24 x 24 x 48, one of these is sufficient. They are BRIGHT.
I know there is the list of FL Chams safe plants, but going through it one by one looking for a trailing flowering plant is super tedious. I wish there were some pics and a little more of a description on that list -
then it would be perfect! Anyway, flowers or colorful plants that preferably trail is what I'm looking for
Not the list I would use, but here are some that include pics.
Safe plant lists:
https://chameleonacademy.com/plants/
https://caskabove.com/chameleon-safe-plants
https://www.madcham.de/en/pflanzen-fuers-terrarium/
Be sure to read all the text & notes.
Inchplants are great, fast-growing, and with decent light will flower (albeit tiny & delicate) to boot. They also have a range of color, depending on age (old growth darker, newer growth lighter.
I also use a climbing/trailing philodendron, golden pothos, and several dracaenas. All will flower when mature.
Another worth checking out IMO is
Madagascar Jasmine if you can find them in your area.
Bromeliads are colorful, but only flower once and they're done.
Unfortunately, the tedium may not be over. As you're looking at plants, you also need to be aware of each plant's
individual needs (water, light, soil, drainage, space, feeding, etc.) and use that information to plan out the enclosure. For example, you don't want to put a full-sun plant at the bottom or where it's shaded by other plants.
Color is great, and different shades & patterns of green can be colorful too.