I use a separate translation service, it makes a copy of my frontend and redirects to another domain. I am using language switcher from this service. since they are not related to magento stores I cannot add my own currency for each store
but, to switch the currency, the service focuses on the language code in my variable $ _SERVER
["HTTP_SERVISE_LANGUAGE"]=> string(2) "fr"
help implement an observer that will change currency depending on the code that comes into the variable $_SERVERS