As far as I can see, the localised currencies are nowhere used, not even in Paypal. Not sure, but that seems to have its own hard coded English list of currencies
$paypalcurrencies = array('USD' => 'US Dollars',
'EUR' => 'Euros',
'JPY' => 'Japanese Yen',
'GBP' => 'British Pounds',
'CAD' => 'Canadian Dollars',
'AUD' => 'Australian Dollars'
I can see your point that it is nice to have the possibility to call something universal as localised currencies. But we can't create and translate all possible lists that any developer might want to use in the core part of the language packs.
We have already +16000 strings, with no way for translators to find out which ones are often used, used for students, sometimes used or never used. That is not very encouraging to start a new language pack.
It also gives a wrong idea about what a good language pack is. E.g while using the Dutch language pack, which is around 80% complete (not currencies ), you will never see any English. But for an outsider, looking at the download page, it seems like there is one out of five strings missing.
So, from a translators point of view, my +1 to keep the number of strings as low as possible and take unused ones, like this set, out of the core language pack.