Reasons my sourdough attempts failed?
The temperature is indeed the most likely reason behind it. In sourdough, you are creating a small new ecosystem niche, and depending on the environmental conditions, different strains of yeast and bacteria will &quot;win&quot; and outgrow the others. And for microorganisms, there is a huge difference between the 18-22 C when your successful colony established itself and the 32 C when you made the second try.
The air humidity is less important, since it is the humidity within the sourdough itself that drives the growth of the microorganisms. There may be a small effect in the initial seeding, with different microorganisms drifting in the air in the different climates. However, I am not sure how much that matters - there are all kinds of conflicting information out there on where your microflora comes from (air or not) and how much influence it has on the final outcome.
I don't think there is much you can do about the whole thing, if you cannot control the temperature. I am not aware of sourdough recipes developed for fermenting at 30 C. If you want to use this recipe, you will have to find a temperature-controlled environment at the right range. Assuming that you don't have that, but have a fridge, you might alternatively try a recipe intended for starting in the fridge. These will give you a different style of sourdough, you will have to decide if you like baking with it.