In the end it is quite simple. My goal was to show a customer only the currency of his billing country, without affecting the chosen language of the shop.
Down below you see a simplified version of what I used to archive that.
The main goal is to force the country (Defined as $new_country_code) to a specific currency (Defined as $multicurrencies)
The snippet checks if the country ($new_country_code) is available within the defined currencies ($multicurrencies) and if so, it will output the language associated with it.
Also, the logic only applies to the frontend.