Error in en message
This is the thread's initial revision.
I've just done my introductory translations but in one of them I noticed the en message was incorrect as well, https://translatewiki.net/wiki/MediaWiki:Donate interface-ARS/en
That should be "Argentine peso", not "Argentinian peso." I've translated it into British English correctly (as it's the same in both en-US and en-GB). But I don't have the permissions to edit that message myself.