I hope the brief tips will help.
Because it's difficult to duplicate or approximate the original environments of full-sun, high heat, especially at night, and because roots can't go deep into the cool moist earth, plants become stressed. They may look great, but things can go bad very quickly. Water, stagnating at the roots, and cool, swampy, water retentive growing mediums kill a lot of plants, and not only Adeniums. Other succulents will also fail.
Growing from seed to flowering is fun for many growers. Their high intensity light requirements need to be met, and keeping the growing medium temps at the right range is difficult without a heat mat. It can be, and is done, by many. Truly, a small heated-in-winter greenhouse can be set up to grow succulents and you don't need a large, expensive growing area, either. You mentioned I think, a sun room? Stick some high intensity lights over the plants and keep them warm. Pot up your Adenium/succulents in a quick-draining, gritty mix, and give it a try.
Warmish growing medium at night, and especially during the cooler winter season.... full sun, or as much full sun as possible -from dawn to dusk....quick-draining, gritty mediums. Plants will grow and flower.
Wishing you happy growing, and many flowers.
