Today I’ve published my first plugin to the SalesforceDX CLI. The plugin is called sfdx-l18n-plugin and allows you to change localisation settings for the user in the scratch org you create. You can query the current values, list the available values from the org and set new values. The plugin can return values in plaintext or as JSON for automation. Changing the org to run in Japanese using Japanese locale and the timezone from Tokyo is as easy as:
sfdx l18n:user:set -u japanese --locale ja_JP --language ja --timezone Asia/Tokyo
You can now easily create a scratch org and change it to run with the required locale, language and/or timezone.