Customer outside the EU – exchange rate

Intra-Community means within Europe. So if your customer is outside the EU, intra-Community never applies anyway.

Exchange rate loss, yes, you will indeed have to fix that yourself. As far as I know, there is no provision for exchange rates in Dexxter, nor do they allow foreign currencies, so it would seem difficult to me.

Just enter it yourself as an expense based on your own document? Cost category something like financial costs, for example?