\{tangent on semantics} At first, reading your comment, I pictured a graph of English words and a graph of Japanese words. If these relationships between words define them, then differences in the graphs explains differences in meaning.
But, though it would be neater for language to be defined within itself, words are references to concepts. Hence, it may be that it's not so much that the node doesn't exist in the other graph, but that the referent doesn't exist. It's one graph (words) relating to another graph (concepts).
We could describe a referent in English, but if it is a complex object with complex relations to other objects, this couldn't be brief; and even if we coined a neologism for it, that new word and concept wouldn't be familiar and integrated into our knowledge graph (and, we wouldn't have experienced it anyway, only read of it).
Possibly, English-speaking expats in Japan could develop slang for those concepts... which would only make sense to them. So they'd probably just use the Japanese words.
But, though it would be neater for language to be defined within itself, words are references to concepts. Hence, it may be that it's not so much that the node doesn't exist in the other graph, but that the referent doesn't exist. It's one graph (words) relating to another graph (concepts).
We could describe a referent in English, but if it is a complex object with complex relations to other objects, this couldn't be brief; and even if we coined a neologism for it, that new word and concept wouldn't be familiar and integrated into our knowledge graph (and, we wouldn't have experienced it anyway, only read of it).
Possibly, English-speaking expats in Japan could develop slang for those concepts... which would only make sense to them. So they'd probably just use the Japanese words.