Unfortunately, you're going to have trouble growing trees inside. You're already experiencing some of the difficulties--low light, extremely low humidity, no air circulation. All are necessary for successful growth, particularly with some seedlings. Without adequate humidity, seedlings can dry out pretty quickly, as they haven't developed enough growth to withstand harsh conditions.
Some tropical species can endure indoor conditions more successfully than temperate zone species. Ficus and schefflera in particular. Flame tree and rosewood are not used all that much in bonsai. Doesn't mean they can't work, but it does mean you're pretty much on your own in discovering what works with them.
Black spruce and Colorado spruce are extremely difficult to cultivate indoors without extreme supplemental lighting, humidification and other aids. They are from extremely high light environment in the wild. They are alpine species for the most part, which means they require extremely high light conditions, direct sun, as well as seasonal temperature changes.
You don't give your location (not specific, geographic location (U.S./state, or country) in your avatar. That's a very important piece of info regarding what you might be able to do and what species and care will work for you.
One last thing, growing from seed is the looooong path to bonsai. You don't do much "bonsai" with seedlings for a very long time, except grow them out until their trunks are adequate for bonsai--trunks and surface root spread are the hearts of good bonsai. It takes a very long time (three, four five, or a few decades) to develop that. Growing them out in containers extends that timeline since pots restrict root growth and subsequently top growth. Some people enjoy growing from seed, though.