My Oriental Worldbuilding

After writing it, I realized that maybe I got a little sidetracked and wrote too much. Maybe the most important part is the questions in bold*...*

Hi. Lately, I’ve been consuming a lot of content on worldbuilding. I hadn’t had much trouble until now, when I wanted to create a living world for my D&D sessions—since I bought a book called Ryoko’s Guide (RGYR)—and by my second narrative session using these mechanics and monsters, I told myself: I need to better solidify my world to run this.

I’ve been trying to create everything—not from scratch, but by drawing on ideas from my early campaigns, content I like, and the games I’ve run. I even have a map ready to go (taken from 2 Minute Tabletop). I’m stuck and need help bringing Asian-inspired cultures and kingdoms to life in my world. I’m struggling not to fall into the trap of dividing it into four “Avatar”-style nations (especially since the rulebook includes a Bender class and spells for the four elements). I tried defining it as five nations based on the Chinese Sacred Beasts (including the Center, the Golden Dragon/Qilin), but I’m having trouble defining what the culture will be like, what that place will be like, and how to avoid tying it to the Sacred Beast’s element or an element of the Godai (the philosophy of the Five Elements).

I’m already out of ideas and came here looking for a little inspiration. If you could help me… Because I’d like each place to offer options for the characters (like in Ember), where someone from a certain region knows things that others don’t (such as languages, a specific profession, or a special trait), but to do that, I need to define…

Does anyone have any advice for me? Or a place where I can do some research or learn how to do good worldbuilding? I’ve already watched tons of videos on YouTube (both in English and Spanish) and checked out websites.

P.S.: I always end up doing the same thing—using Asian cultures as a reference—and I’m trying to use them because I thought about dividing them into Japanese, Chinese, Korean, and Indian cultures and seeing if I could mix them with Western cultures to give them some “flavor,” like a Korean-Nordic mix, but I don’t know… I feel like I don’t have what it takes to properly define the nations or kingdoms.

Please excuse my English; I relied heavily on a translator since it's not my native language.