I don't know, although I doubt that there is/are any translation(s) of PMEG into national / ethnic languages. I myself see no need for them. My native language is English, and historically there have been many grammar books about English, themselves written in English itself. The same for French and I am sure for many, many other major languages with literate readers. Yes, there are some grammar books about Language X written in Language Y, but not always. I myself refer to PMEG only occasionally for fine points, but I can already read enough of Esperanto that (using a dictionary if need be) I can consult the work without difficulty. To the best of my understanding, PMEG is a more advanced reference work suitable for those who already have a minimally working knowledge of the language.