Is there any way to restrict the language of first name, last name and username to korean in keycloak?

I am writing a website in Nuxt that only supports one language. I am using keycloak as an Auth Service.

On the website, I want to restrict the language of some fields like username, first and last name. The rest of the website is in Korean and the username should also be in korean.

Should I make a custom theme and handle it in the front end? I am using docker container for keycloak. How should I apply my own custom theme through docker?

I was also thinking of maybe using keycloak rest api to create my own custom signup and login form in my nuxt application. But I don’t know how to handle it with keycloak-js. Should I just stop using keycloak-js and just use restapi for everything or I can use them both at the same time?

Is there any other simpler way to handle this?

What would be the best way to handle this?

Thanks in advance.