Can the payment page be defined in three languages to switch?
What languages are you wanting it to switch too? 
- Russian and Sibaya
If you setLocale then you can set the language of the form. If the language returned by navigator.language is unsupported, the SDK falls back to en-US.
If the specified language passed to setLocale() is not supported, the operation is a no-op. If the specified language is supported, but the specified region is not, Web Payments SDK will fall back to using the desired language in a different supported region.