The fact that some terms and ideas do not directly translate to one's native language from Japanese (or other non-romance languages). You can oversimplify a term with an english word, but that often leads to a loss in translation. I know some people are afraid of being accused of being a Japanophile, but at the same time some ideas just don't hold the same symbolic meaning in english terms as they do in their native language.
That's true, as far as the terms themselves go. But what value do you get from changing your social model in order to understand those ideas - which are not Budo ideas, per se?
Are you saying that someone could not understand Aikido without going back to the Japanese mindset?
I've practiced in Japanese dojo in Japan, FWIW, that cared nothing for sempai-kohai.