The answer to your specific question about  hataraku is a no also The onyomi was based on the right half of the character which is Chinese Chinese  vs Japanese  The Japanese character  is never used in Chinese Do a search in Google and specify this character and restrict the result to Chinese pages only You will some webpages using this character but they are mostly Japanese pages mislabeled as Chinese pages They are some Chinese pages using this character in the context of referring to the Japanese Labor ministry I dont count that as reverse importation IMHO the statement in the article about reverse importation is incorrect