imo these instructions look horribly overcomplicated, but maybe the simple way just doesent work for some people. the usual way is just install eastern languages if they arent installed, download applocale, run the RTP with applocale, unzip yume 2kki, and play the game with applocale in japanese, creating a shortcut so you dont have to go and select it every time
that vista security stuff is bs and doesent need to be done, no idea about 7 because i think ive only done it on home ultimate, but it shouldnt be that different