LvH SEPA means Single Euro Payment Area. How do you think that is used also for (as an example) US Dollars? Take a look at this brochure for SEPA from the European Central Bank: https://www.ecb.europa.eu/paym/retpaym/shared/pdf/SEPA_e-brochure_2013.pdf and on page 5 you can read quotes like these "one currency: the euro is the monetary basis for SEPA. The single currency is the political driver for the establishment of a common market for payments". If you want to transfer GBP then you get "No SEPA transfer for you!" (with apologies to Seinfeld).
Just because there are banks in the EU that allow you to keep an account in a non-Euro currency doesn't mean that all banks in the EU should accept all those currencies for transfers.
SWIFT transfers can be done in several currencies, however the price list only mentions inbound swift costs for transfers in euro amounts (depending on the amount the costs go up). It doesn't state any price for an amount in USD.
I do think they should add a line in the priclist stating only euro transfers are allowed, though. Just to make it more clear.
So if you have an account in British Pounds and you want to transfer it to another bank you need to use a SWIFT transfer (assuming they aren't two banks in the UK). And SWIFT is a large pitfall of costs, rules, errors and what not. So bunq should add they only want to receive euro and don't do any currency conversion themselves when receiving SWIFT (and perhaps other rules they have for their SWIFT transfers).
