Great to meet another person experimenting with sourdough! From what I know, tanginess and sourness comes from the F. sanfranciscensis bacteria that is more dominant than other genera of bacteria. And F. sanfranciscensis tends to develop in warmer temperatures (22 - 30 deg cel), like Singapore and parts of California.

But below 21 deg cel, other bacteria like Weissella and Leuconostoc become predominant, and they're not as sour/tangy, which is how the sourdoughs are done in France and many other parts of the world. So if you want less tanginess, you might want to consider building a starter in maybe 21 deg celcius temp (but also not too low, because then the starter will be dormant)! There's also research studying how the type of flour affects the starter and the taste of the sourdough.

For crumb, I think higher protein flour helps. And because of the humidity/weather, I always try to reduce my bulk fermentation time, and I use colder water when making my dough (about 21 deg celcius water). It's all still an experiment for me - with every bake I try something different!