Nobody cares about a german/swedish/brazilian etc. band singing in english and having an english name. A finnish band singing in Swedish doesn't even raise an eyebrow (see Finntroll). A german band singing in French would be considered curious, but they wouldn't get hated for it. An english band singing in Kiswahili would be considered exotic, but they wouldn't be hated for it.
Only the japanese language is considered so sacrosanct by fans that it may never me used in lyrics by any gaijin band. Ever.