With regards to fora, it's wrong. It is a spurious argument to claim that a loan word should follow the rules of the language it comes from. How many people know the Inuit pluralisation rules for 'anorak', or the Nahautl rules for 'avocado'. If we borrow a Japanese word, can't we make it plural because Japanes has no plural? Where should we draw the line? Japanese does not accept an inanimate noun as a subject; should we follow this rule, too?