On a landing page for a Pricefx instance, you can use these parameters in links to different language versions:
locale– Sets the format of dates and numbers.uiLanguage– Sets the language of the application. If not specified, the default language from User Settings or the language setting of your web browser will be applied.
As a value for both parameters, use the ISO language code.
For example, the last link on the screenshot below looks like this: https://test.pricefx.eu/classic/priceFxWeb.html?locale=de&uiLanguage=en#loginPage
It keeps the UI in English, while dates and numbers are formatted according to German. 
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