I'm not trying to somehow place blame for the tree's death, only suggesting things that might have killed it. Overwatering is simply not an issue with BC in containers, especially in the free draining soil mix you're using. Your idea that the hot water from the hose is probably on the money.
"I don't have time to track it down right now but this subspecies came from Australia."
FWIW, Bald Cypress is strictly a native North American species. It is not native to Australia. While this particular tree may have its individual origin in Australia, it's originally from a North America ancestor imported in the last century or so and cloned there for its weeping growth habit.
This is a cultivar, not a subspecies. There is a difference. Subspecies is a specific term that indicates a separate race of a species, that is genetically distiguishable from the main population, typically based on geographic location. Its takes thousands of years for such genetic diversity to develop for a subspecies to branch off of the main species.
A
cultivar is a plant or group of plants selected by man for desirable characteristics that can be maintained by propagation--typically by cloning--cuttings are clones... Cultivars are the product of direct human selection, not natural selection.
All this sounds kinda beside the point, but it's really not. This plant is not of a separate race of BC that has different requirements or needs or adaptations.