Stephania
Many people treat it as a succulent. It likes a well drained soil mix. While dormant it should be watered less but when shoots appear it can be water like any other plant. My main concern would be your heat though. I have trouble with mine as well. I started out with six plants now I am down to three. I have tried to get them to seed but the heat doesnt help much. It does hybridize with other impatiens like auricoma and bicaudata. The seed line of Impatiens African Orchid maybe hybrids with something very close to tuberosa. The main parent is auricoma for sure.

Thank you Derick!
Just today morning, I found my only one left plant has started shooting 2-3 buds on the top of caudex. So I watered with some fungicide and moved it to get more sunlight .

As I was told from my Madagascar friend that the plant came from an Island in north Madagascar. The plant found on limestone mountain with tropical climate, so he stated I could keep this one, but !!! anyways I'll try my best.

PS. After beginning of our rainy season, which quite late this year, my Impatiens mirabilis are now set some seed pot. Strange, I found that some seedlings from the white-pink flower, they appear to be yellow flower!!