Water isn't entirely at fault, it's the temperature fluctuation in addition to our dry conditions.
Have you noticed lately it's been in the low 40's in the evening and high 80's in the day?
Yea, that will cause some good cracking to just about any fruit.
Happened to my longans, mangoes, cherimoyas, atemoyas, jujube + many others last year.
The mangoes to go about the size of a child's fist and starts cracking down the center.
Maha, Sia Tong, Okrung, Keo Savoy mangoes.
I'm not sure if you measure your parameters inside your greenhouse, but I try to keep my humidity, temp and CO2/O2 levels at safe levels.
So far it's helping this year, because it is a challenge to grow anything tropical/sub-tropical here in the Bay Area.