We have designed Easy Digital Downloads EU VAT to work with multi-lingual and multi-currency plugins.
For example, if you wish to translate your website into other languages then you can use a plugin such as WeGlot, TranslatePress or WPML. All the text in the plugin (e.g. 'VAT Number') is added as internationalized strings in the code. As a result, you can use the string translations feature in your multilingual plugin to translate this text.
If you wish to allow your users to pay in multiple currencies then we recommend Aelia's Currency Switcher for Easy Digital Downloads plugin, which we have tested with (and use on our own site).