You need more light. Artificial light with a timer. Fan blowing 24/7. You are good on the fertilizer unless it is mostly nitrogen. What is the formulation? NPK...the N has to be lower than the P and the K or you will get vegetative growth not reproductive. Need a great grow light with ballast and two different sets of grow bulbs; one in blue and one in red. 18hours minimum with the blue light then when you want to force seed go to 12 hours light/12 hours dark using the red bulbs. No light at all during the dark phase. It will be worth it for your customers to see and learn? Is this your coffee shop? What is the pH of your soil? The blowing air will help your plant take in CO2 as the blowing air removes the O2 from the leaves allowing for CO2 to be more available, better growth. (Have your customers BREATHE out on your plants giving them more CO2...one caveat however, no one that smokes, okay)? Also less fungus worries. Also, the blowing air will fertilize your self fertile plant.
You have to acclimate a plant going from indoors to out of doors in the sun. The same taking a plant from out of doors used to sunlight to the indoor environment. It is gradual, critical and takes some time. I have to say how beautiful your plant looks! If you want beans though you have to increase the light artificially. Great project and your plant is such a cutie!
Any plant that you want to produce flowers or fruit needs much more light. The fertilizer thing is important because if you are giving it too much nitrogen that will only promote vegetative growth not flowers and fruit.
Otherwise, what a lovely little tree! You could tie lots of beans on your tree like ornaments as it sits beneath a great light getting used to its own environment and timing of light/dark cycles. Don't transplant it until after setting seed. Then a pot only a few inches wider in diameter. I'd go with clay, a saucer and pot feet to raise the bottom of the pot off the surface. No rocks or gravel just potting soil in your pot with the plant. No moisture holding gimmicks and no added fertilizer in that potting soil. Just plain potting soil. Try to use a chlorine and fluoride free water instead of tap water.