I don't speak the language but I would risk to say that the qualification is the same, only the King's actual TITLE is higher so I think the rulers use the qualification of HRH as opposed to HM to make it clearer in English that the title of Yang di-Pertuan Agong is higher than the title of the ruler of each of the state while the qualification remains the same in Malaysian.
So my theory is that it is all about the translation. After all "Duli Yang Maha Mulia" used to be translated as HH in the colonial times to make the ruler's status even lower while compared to the King or Queen of the UK. Again, my interpretation.
: --Previous Message--
: Quite an interesting information, the Sultan
: of Johor has recently decided to use the
: qualification of Majesty as the official
: English translation of "Duli Yang Maha
: Mulia", it used to be His Royal
: Highness (as it is the case of all the other
: "royal rulers" in Malaysia).
: What is the style for the King of Malaysia?