today_ai_weather/config/initializers/locale.rb

# config/initializers/locale.rb
require "i18n/backend/fallbacks"

# Where the I18n library should search for translation files
I18n.load_path += Dir[Rails.root.join("config", "locales", "*.{rb,yml}")]

# Permitted locales available for the application
I18n.available_locales = [ :en, :"zh-CN", :ja, :ko ]

I18n::Backend::Simple.send(:include, I18n::Backend::Fallbacks)
# I18n::Backend::Simple.include I18n::Backend::Fallbacks
# I18n.fallbacks[:en]
I18n.fallbacks = I18n::Locale::Fallbacks.new(
  en: [ :en ],
  'zh-CN': [ :zh, :zh_cn, :en ]
)

# Set default locale to something other than :en
I18n.default_locale = :en